cdc guidelines for well child visits

What Exposure Questions Should Be Included in a Well Child Visit?

Learning Objective
Taking a Screening Exposure History for the Well Child
Questions for Well Baby Visits
Questions to Ask Parent During a Well Toddler and Young School-age Child Visit
Questions for Well Adolescent Visit
Progress Check

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Upon completion of this section, you will be able to

describe how to take a screening exposure history for a well child visit.

Pediatricians should take two environmental medicine actions for every well child who presents to an office or a clinic.

A routine screening history for potential environmental exposures.
If necessary, age-appropriate risk-based screening for lead poisoning, using the Centers for Disease Control and Prevention’s (CDC) lead poisoning prevention guidelines [CDC 1997].

A general pediatrician’s practice allows little time for an extensive environmental exposure history. However, initial and subsequent well child visits do give pediatricians opportunities to provide parents and caregivers with educational materials on preventing exposures and actions to take if an exposure occurs. Table 2 lists recommended screening questions and appropriate corrective actions. A written checklist completed by parents may be used to facilitate obtaining the history.

An example of this checklist is the National Environmental Education Foundation Screening Environmental History Form [PDF – 112 KB] at http://www.neefusa.org/health/PEHI/HistoryForm.htm .

The following questions can help pediatricians assess environmental exposures especially relevant to infants.

For a routine well toddler or young school-age visit, pediatricians should ask the following screening questions in order to determine if any toxic exposures are occurring:

The following screening questions should be asked during all well adolescent visits.

An initial well child visit presents an excellent opportunity to ask basic screening questions about common environmental hazards, including lead exposure.
It is important to incorporate age-appropriate questions about environmental hazards during other routine office visits.
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Preventive Health Care Visits in Infants

Healthy infants should be seen by their doctor often during the first year of life. Preventive health care visits (also called well-child visits) typically take place within a few days after birth or by 2 weeks of age and at 1, 2, 4, 6, and 9 months of age. During these visits, the doctor uses age-specific guidelines to monitor the infant's growth and development and asks the parents questions about various developmental milestones (see table Developmental Milestones From Birth to Age 12 Months ). Tests are sometimes done, and during many visits, the doctor vaccinates the infant against various illnesses (see Childhood Vaccination Schedule ).

Health care visits also allow the doctor to educate the parents about eating, sleeping, behavior, child safety, nutrition, exercise, and good health habits. In addition, the doctor advises the parents what developmental changes to expect in their infant by the next visit.

Examination

The infant's length and height , weight , and head circumference are measured at every visit. The doctor examines the infant for various abnormalities, including signs of hereditary disorders or birth defects .

The eyes are examined, and vision is tested. Infants who were born very prematurely (before the completion of 32 weeks of development in the uterus) usually need more frequent eye examinations by an eye specialist to look for retinopathy of prematurity , which is an eye disease that occurs when infants are born before the blood vessels in their eyes are fully developed and may result in blindness, and for the development of refractive errors , which result in blurring of vision. These disorders are more common among infants who were born very prematurely.

The doctor checks the infant’s hips for signs that the hip joints are loose or dislocated ( developmental dysplasia of the hip ). The doctor checks the infant's teeth , if they are present, for cavities and the mouth for thrush , which is a common yeast infection among infants.

The doctor also examines the heart, lungs, abdomen, arms and legs, and genitals.

Screening tests are done to assess whether infants are at risk of certain disorders.

Blood tests are done to detect anemia , sickle cell disease , and exposure to lead .

Hearing tests are done shortly after birth to determine whether an infant has a hearing disorder or hearing loss (see Newborn Screening Tests ) and are repeated later if new concerns about the infant's hearing develop (see also Hearing Impairment in Children ).

Infants are screened for tuberculosis (TB) risk factors with a questionnaire at all well-child visits, usually beginning in infancy. Risk factors include exposure to TB, being born in or having traveled to areas of the world where TB is common (countries other than the United States, Canada, Australia, and New Zealand and Western and North European countries), having a family member with TB, and having parents or close contacts who are recent immigrants from an area where TB is common or who have recently been in jail. Those with risk factors usually have tuberculosis screening tests done.

At these visits, the doctor gives parents age-appropriate safety guidelines.

The following safety guidelines apply to infants from birth to age 12 months:

Use a rear-facing car seat and place it in the back seat of the vehicle.

Set the hot water heater to 120° F or less.

Prevent falls from changing tables and around stairs.

Place infants on their back to sleep on a firm, flat mattress for every sleep, do not share a bed, and do not place pillows, bumper pads, nonfitted sheets, stuffed animals or other toys, quilts, comforters, or weighted or loose blankets in the crib. (See also sidebar Safe to Sleep: Reducing the Risk of SIDS .)

Do not give infants foods and objects that can cause choking or be inhaled into the lungs.

Do not use baby walkers.

Place safety latches on cabinets and cover electrical outlets.

Remain alert when watching infants in the bathtub or near a pool or any body of water and when they are learning to walk.

Image courtesy of the Centers for Disease Control and Prevention (CDC), National Center for Injury Prevention and Control ( Transportation Safety Resources ). This guidance from the CDC is for the United States, and regulations may differ in other countries.

Nutrition and exercise

For infants, recommendations for nutrition are based on age. The doctor can help parents weigh the benefits of breastfeeding versus formula-feeding and give guidance regarding solid foods .

Parents should provide infants with a safe environment they can roam in and explore. Outdoor play should be encouraged from infancy.

Screen time (for example, television, video games, cell phones and other handheld devices, and noneducational computer time) may result in inactivity and obesity. Limits on the time a child spends using devices with screens should start at birth and be maintained throughout adolescence.

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Well Child Visits: What Parents Need to Know

Most parents instinctually know when something “isn’t quite right” with their child and it is time to bring them to a clinic to be checked. It just so happens that well child check visits are equally as important for healthy children.

Well child visits are a time when parents check up on their child’s health and make sure they are growing and developing in the healthiest way possible. The visits usually start a few days after a child is born and continue until they turn 18 years old, after which they transition to a doctor specializing in adult health. A pediatrician or a family medicine provider typically completes the well child checks.

Since the beginning of the 2020 pandemic, the American Academy of Pediatrics has documented a significant drop in the number of parents bringing their children in for well child checks and we’ve experienced the same in Fairbanks. We encourage families to schedule over-due and upcoming visits right away. Well child visits are very important for ALL kids, especially those 24 months and younger, and it is recommended to keep these appointments on schedule.

During a well-child visit, your provider will:

There is so much to discuss and address at your child’s appointment. No matter how old your kids are, being properly prepared for annual well visits is a great way to ensure you get the most benefit out of the time you have with your child’s health care provider. Here are five quick tips to help ensure time is well spent during your well child check:

In general, it’s recommended that you follow the following guidelines for how often your child receives a well-child visit (beginning with the soonest visit after birth):

Newborn (generally 2 or 3 days after discharge)
2 and a half years
Once a year every year until age 18

If you have questions or need more information about well-child care visits, speak with your health care provider today. We want to help keep your child in the best health possible.

Dr. Carla Cartagena De Jesus is a physician in the Foundation Health Partners Pediatrics Department. Dr. Cartagena De Jesus graduated from the University of Alaska Fairbanks before completing her schooling at the University of Washington and her residency at the University of Arizona.

Family Life

AAP Schedule of Well-Child Care Visits

Parents know who they should go to when their child is sick. But pediatrician visits are just as important for healthy children.

The Bright Futures /American Academy of Pediatrics (AAP) developed a set of comprehensive health guidelines for well-child care, known as the " periodicity schedule ." It is a schedule of screenings and assessments recommended at each well-child visit from infancy through adolescence.

Schedule of well-child visits

The first week visit (3 to 5 days old)
1 month old
2 months old
4 months old
6 months old
9 months old
12 months old
15 months old
18 months old
2 years old (24 months)
2 ½ years old (30 months)
3 years old
4 years old
5 years old
6 years old
7 years old
8 years old
9 years old
10 years old
11 years old
12 years old
13 years old
14 years old
15 years old
16 years old
17 years old
18 years old
19 years old
20 years old
21 years old

The benefits of well-child visits

Prevention . Your child gets scheduled immunizations to prevent illness. You also can ask your pediatrician about nutrition and safety in the home and at school.

Tracking growth & development . See how much your child has grown in the time since your last visit, and talk with your doctor about your child's development. You can discuss your child's milestones, social behaviors and learning.

Raising any concerns . Make a list of topics you want to talk about with your child's pediatrician such as development, behavior, sleep, eating or getting along with other family members. Bring your top three to five questions or concerns with you to talk with your pediatrician at the start of the visit.

Team approach . Regular visits create strong, trustworthy relationships among pediatrician, parent and child. The AAP recommends well-child visits as a way for pediatricians and parents to serve the needs of children. This team approach helps develop optimal physical, mental and social health of a child.

More information

Back to School, Back to Doctor

Recommended Immunization Schedules

Milestones Matter: 10 to Watch for by Age 5

Your Child's Checkups

Bright Futures/AAP Recommendations for Preventive Pediatric Health Care (periodicity schedule)

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Redesigning Primary Care Well Child Visits: A Group Model

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Ashley Blanchard , Bianca Calderon , Erin Cahill , Amanda Gonzalez , Dodi Meyer , Margaret C. Krause , Suzanne Friedman; Redesigning Primary Care Well Child Visits: A Group Model. Pediatrics January 2018; 141 (1_MeetingAbstract): 41. 10.1542/peds.141.1MA1.41

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Background: Providing effective, efficient well child-care can be challenging. Many obstacles exist for delivering well child-care to low-income populations including time, cultural barriers and limited resources. Urban, immigrant populations face unique social circumstances and stand to benefit from a model of care that provides parents with enhanced support and education. Group well child-care is a novel take on the traditional visit, creating a community of parents with similarly aged children with a consistent provider for the first year of life. This model allows parent driven conversation, increased provider contact and additional time to convey anticipatory guidance. Objective: Our goal is to create a sustainable model for delivery of group well child-care during the first year of life in a mixed faculty resident practice. We aim to integrate multiple healthcare team members to provide care based on the AAP Bright Futures guidelines. We plan to assess if this model improves health outcomes compared to traditional care. Design/Methods: Patients participating in group visits, as well as age matched infants receiving traditional care, were recruited from the Ambulatory Care Network of New York Presbyterian Hospital. The group well visit curriculum was created based on AAP guidelines with emphasis on topics that are culturally relevant. Visits are interactive sessions that encourage parent driven discussion and highlight themes in preventative pediatrics. Visits are led by pediatric faculty and residents with guests from different specialties, including social work, dental, nutrition and obstetrics-gynecology discussing pertinent topics at age specific visits. Outcomes include both feasibility measures as well as health outcomes. Some of the outcomes being tracked include: length of visit, attendance rate, emergency room utilization, preventative care screening, and perception of social support. Results: Currently, we have 7 active groups across 3 practice sites with 56 families participating. To date, results show comparable patient satisfaction, attendance rates and length of visit to traditional care. Additionally, anticipatory guidance retention and screening for domestic violence and postpartum depression are increased in intervention groups. Conclusions: Group well child-care promises to be an innovative, sustainable and efficient model for healthcare delivery in a practice serving low-income populations. Although time spent in clinic is similar in both groups, the families enrolled in group care spend the entire length of the visit, face to face with a physician provider. Patients stand to greatly benefit from this model that allows for longer provider-patient interactions, increased knowledge retention, increased screening and enhanced social support without compromising patient satisfaction, access nor efficiency.

Initial Visit and Screening Data

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KATHERINE TURNER, MD

Am Fam Physician. 2018;98(6):347-353

Related letter: Well-Child Visits Provide Physicians Opportunity to Deliver Interconception Care to Mothers

Author disclosure: No relevant financial affiliations.

The well-child visit allows for comprehensive assessment of a child and the opportunity for further evaluation if abnormalities are detected. A complete history during the well-child visit includes information about birth history; prior screenings; diet; sleep; dental care; and medical, surgical, family, and social histories. A head-to-toe examination should be performed, including a review of growth. Immunizations should be reviewed and updated as appropriate. Screening for postpartum depression in mothers of infants up to six months of age is recommended. Based on expert opinion, the American Academy of Pediatrics recommends developmental surveillance at each visit, with formal developmental screening at nine, 18, and 30 months and autism-specific screening at 18 and 24 months; the U.S. Preventive Services Task Force found insufficient evidence to make a recommendation. Well-child visits provide the opportunity to answer parents' or caregivers' questions and to provide age-appropriate guidance. Car seats should remain rear facing until two years of age or until the height or weight limit for the seat is reached. Fluoride use, limiting or avoiding juice, and weaning to a cup by 12 months of age may improve dental health. A one-time vision screening between three and five years of age is recommended by the U.S. Preventive Services Task Force to detect amblyopia. The American Academy of Pediatrics guideline based on expert opinion recommends that screen time be avoided, with the exception of video chatting, in children younger than 18 months and limited to one hour per day for children two to five years of age. Cessation of breastfeeding before six months and transition to solid foods before six months are associated with childhood obesity. Juice and sugar-sweetened beverages should be avoided before one year of age and provided only in limited quantities for children older than one year.

Well-child visits for infants and young children (up to five years) provide opportunities for physicians to screen for medical problems (including psychosocial concerns), to provide anticipatory guidance, and to promote good health. The visits also allow the family physician to establish a relationship with the parents or caregivers. This article reviews the U.S. Preventive Services Task Force (USPSTF) and the American Academy of Pediatrics (AAP) guidelines for screenings and recommendations for infants and young children. Family physicians should prioritize interventions with the strongest evidence for patient-oriented outcomes, such as immunizations, postpartum depression screening, and vision screening.

Clinical Examination

The history should include a brief review of birth history; prematurity can be associated with complex medical conditions. 1 Evaluate breastfed infants for any feeding problems, 2 and assess formula-fed infants for type and quantity of iron-fortified formula being given. 3 For children eating solid foods, feeding history should include everything the child eats and drinks. Sleep, urination, defecation, nutrition, dental care, and child safety should be reviewed. Medical, surgical, family, and social histories should be reviewed and updated. For newborns, review the results of all newborn screening tests ( Table 1 4 – 7 ) and schedule follow-up visits as necessary. 2

PHYSICAL EXAMINATION

A comprehensive head-to-toe examination should be completed at each well-child visit. Interval growth should be reviewed by using appropriate age, sex, and gestational age growth charts for height, weight, head circumference, and body mass index if 24 months or older. The Centers for Disease Control and Prevention (CDC)-recommended growth charts can be found at https://www.cdc.gov/growthcharts/who_charts.htm#The%20WHO%20Growth%20Charts . Percentiles and observations of changes along the chart's curve should be assessed at every visit. Include assessment of parent/caregiver-child interactions and potential signs of abuse such as bruises on uncommonly injured areas, burns, human bite marks, bruises on nonmobile infants, or multiple injuries at different healing stages. 8

The USPSTF and AAP screening recommendations are outlined in Table 2 . 3 , 9 – 27 A summary of AAP recommendations can be found at https://www.aap.org/en-us/Documents/periodicity_schedule.pdf . The American Academy of Family Physicians (AAFP) generally adheres to USPSTF recommendations. 28

MATERNAL DEPRESSION

Prevalence of postpartum depression is around 12%, 22 and its presence can impair infant development. The USPSTF and AAP recommend using the Edinburgh Postnatal Depression Scale (available at https://www.aafp.org/afp/2010/1015/p926.html#afp20101015p926-f1 ) or the Patient Health Questionnaire-2 (available at https://www.aafp.org/afp/2012/0115/p139.html#afp20120115p139-t3 ) to screen for maternal depression. The USPSTF does not specify a screening schedule; however, based on expert opinion, the AAP recommends screening mothers at the one-, two-, four-, and six-month well-child visits, with further evaluation for positive results. 23 There are no recommendations to screen other caregivers if the mother is not present at the well-child visit.

PSYCHOSOCIAL

With nearly one-half of children in the United States living at or near the poverty level, assessing home safety, food security, and access to safe drinking water can improve awareness of psychosocial problems, with referrals to appropriate agencies for those with positive results. 29 The prevalence of mental health disorders (i.e., primarily anxiety, depression, behavioral disorders, attention-deficit/hyperactivity disorder) in preschool-aged children is around 6%. 30 Risk factors for these disorders include having a lower socioeconomic status, being a member of an ethnic minority, and having a non–English-speaking parent or primary caregiver. 25 The USPSTF found insufficient evidence regarding screening for depression in children up to 11 years of age. 24 Based on expert opinion, the AAP recommends that physicians consider screening, although screening in young children has not been validated or standardized. 25

DEVELOPMENT AND SURVEILLANCE

Based on expert opinion, the AAP recommends early identification of developmental delays 14 and autism 10 ; however, the USPSTF found insufficient evidence to recommend formal developmental screening 13 or autism-specific screening 9 if the parents/caregivers or physician have no concerns. If physicians choose to screen, developmental surveillance of language, communication, gross and fine movements, social/emotional development, and cognitive/problem-solving skills should occur at each visit by eliciting parental or caregiver concerns, obtaining interval developmental history, and observing the child. Any area of concern should be evaluated with a formal developmental screening tool, such as Ages and Stages Questionnaire, Parents' Evaluation of Developmental Status, Parents' Evaluation of Developmental Status-Developmental Milestones, or Survey of Well-Being of Young Children. These tools can be found at https://www.aap.org/en-us/advocacy-and-policy/aap-health-initiatives/Screening/Pages/Screening-Tools.aspx . If results are abnormal, consider intervention or referral to early intervention services. The AAP recommends completing the previously mentioned formal screening tools at nine-, 18-, and 30-month well-child visits. 14

The AAP also recommends autism-specific screening at 18 and 24 months. 10 The USPSTF recommends using the two-step Modified Checklist for Autism in Toddlers (M-CHAT) screening tool (available at https://m-chat.org/ ) if a physician chooses to screen a patient for autism. 10 The M-CHAT can be incorporated into the electronic medical record, with the possibility of the parent or caregiver completing the questionnaire through the patient portal before the office visit.

IRON DEFICIENCY

Multiple reports have associated iron deficiency with impaired neurodevelopment. Therefore, it is essential to ensure adequate iron intake. Based on expert opinion, the AAP recommends supplements for preterm infants beginning at one month of age and exclusively breastfed term infants at six months of age. 3 The USPSTF found insufficient evidence to recommend screening for iron deficiency in infants. 19 Based on expert opinion, the AAP recommends measuring a child's hemoglobin level at 12 months of age. 3

Lead poisoning and elevated lead blood levels are prevalent in young children. The AAP and CDC recommend a targeted screening approach. The AAP recommends screening for serum lead levels between six months and six years in high-risk children; high-risk children are identified by location-specific risk recommendations, enrollment in Medicaid, being foreign born, or personal screening. 21 The USPSTF does not recommend screening for lead poisoning in children at average risk who are asymptomatic. 20

The USPSTF recommends at least one vision screening to detect amblyopia between three and five years of age. Testing options include visual acuity, ocular alignment test, stereoacuity test, photoscreening, and autorefractors. The USPSTF found insufficient evidence to recommend screening before three years of age. 26 The AAP, American Academy of Ophthalmology, and the American Academy of Pediatric Ophthalmology and Strabismus recommend the use of an instrument-based screening (photoscreening or autorefractors) between 12 months and three years of age and annual visual acuity screening beginning at four years of age. 31

IMMUNIZATIONS

The AAFP recommends that all children be immunized. 32 Recommended vaccination schedules, endorsed by the AAP, the AAFP, and the Advisory Committee on Immunization Practices, are found at https://www.cdc.gov/vaccines/schedules/hcp/child-adolescent.html . Immunizations are usually administered at the two-, four-, six-, 12-, and 15- to 18-month well-child visits; the four- to six-year well-child visit; and annually during influenza season. Additional vaccinations may be necessary based on medical history. 33 Immunization history should be reviewed at each wellness visit.

Anticipatory Guidance

Injuries remain the leading cause of death among children, 34 and the AAP has made several recommendations to decrease the risk of injuries. 35 – 42 Appropriate use of child restraints minimizes morbidity and mortality associated with motor vehicle collisions. Infants need a rear-facing car safety seat until two years of age or until they reach the height or weight limit for the specific car seat. Children should then switch to a forward-facing car seat for as long as the seat allows, usually 65 to 80 lb (30 to 36 kg). 35 Children should never be unsupervised around cars, driveways, and streets. Young children should wear bicycle helmets while riding tricycles or bicycles. 37

Having functioning smoke detectors and an escape plan decreases the risk of fire- and smoke-related deaths. 36 Water heaters should be set to a maximum of 120°F (49°C) to prevent scald burns. 37 Infants and young children should be watched closely around any body of water, including water in bathtubs and toilets, to prevent drowning. Swimming pools and spas should be completely fenced with a self-closing, self-latching gate. 38

Infants should not be left alone on any high surface, and stairs should be secured by gates. 43 Infant walkers should be discouraged because they provide no benefit and they increase falls down stairs, even if stair gates are installed. 39 Window locks, screens, or limited-opening windows decrease injury and death from falling. 40 Parents or caregivers should also anchor furniture to a wall to prevent heavy pieces from toppling over. Firearms should be kept unloaded and locked. 41

Young children should be closely supervised at all times. Small objects are a choking hazard, especially for children younger than three years. Latex balloons, round objects, and food can cause life-threatening airway obstruction. 42 Long strings and cords can strangle children. 37

DENTAL CARE

Infants should never have a bottle in bed, and babies should be weaned to a cup by 12 months of age. 44 Juices should be avoided in infants younger than 12 months. 45 Fluoride use inhibits tooth demineralization and bacterial enzymes and also enhances remineralization. 11 The AAP and USPSTF recommend fluoride supplementation and the application of fluoride varnish for teeth if the water supply is insufficient. 11 , 12 Begin brushing teeth at tooth eruption with parents or caregivers supervising brushing until mastery. Children should visit a dentist regularly, and an assessment of dental health should occur at well-child visits. 44

SCREEN TIME

Hands-on exploration of their environment is essential to development in children younger than two years. Video chatting is acceptable for children younger than 18 months; otherwise digital media should be avoided. Parents and caregivers may use educational programs and applications with children 18 to 24 months of age. If screen time is used for children two to five years of age, the AAP recommends a maximum of one hour per day that occurs at least one hour before bedtime. Longer usage can cause sleep problems and increases the risk of obesity and social-emotional delays. 46

To decrease the risk of sudden infant death syndrome (SIDS), the AAP recommends that infants sleep on their backs on a firm mattress for the first year of life with no blankets or other soft objects in the crib. 45 Breastfeeding, pacifier use, and room sharing without bed sharing protect against SIDS; infant exposure to tobacco, alcohol, drugs, and sleeping in bed with parents or caregivers increases the risk of SIDS. 47

DIET AND ACTIVITY

The USPSTF, AAFP, and AAP all recommend breastfeeding until at least six months of age and ideally for the first 12 months. 48 Vitamin D 400 IU supplementation for the first year of life in exclusively breastfed infants is recommended to prevent vitamin D deficiency and rickets. 49 Based on expert opinion, the AAP recommends the introduction of certain foods at specific ages. Early transition to solid foods before six months is associated with higher consumption of fatty and sugary foods 50 and an increased risk of atopic disease. 51 Delayed transition to cow's milk until 12 months of age decreases the incidence of iron deficiency. 52 Introduction of highly allergenic foods, such as peanut-based foods and eggs, before one year decreases the likelihood that a child will develop food allergies. 53

With approximately 17% of children being obese, many strategies for obesity prevention have been proposed. 54 The USPSTF does not have a recommendation for screening or interventions to prevent obesity in children younger than six years. 54 The AAP has made several recommendations based on expert opinion to prevent obesity. Cessation of breastfeeding before six months and introduction of solid foods before six months are associated with childhood obesity and are not recommended. 55 Drinking juice should be avoided before one year of age, and, if given to older children, only 100% fruit juice should be provided in limited quantities: 4 ounces per day from one to three years of age and 4 to 6 ounces per day from four to six years of age. Intake of other sugar-sweetened beverages should be discouraged to help prevent obesity. 45 The AAFP and AAP recommend that children participate in at least 60 minutes of active free play per day. 55 , 56

Data Sources: Literature search was performed using the USPSTF published recommendations ( https://www.uspreventiveservicestaskforce.org/BrowseRec/Index/browse-recommendations ) and the AAP Periodicity table ( https://www.aap.org/en-us/Documents/periodicity_schedule.pdf ). PubMed searches were completed using the key terms pediatric, obesity prevention, and allergy prevention with search limits of infant less than 23 months or pediatric less than 18 years. The searches included systematic reviews, randomized controlled trials, clinical trials, and position statements. Essential Evidence Plus was also reviewed. Search dates: May through October 2017.

Gauer RL, Burket J, Horowitz E. Common questions about outpatient care of premature infants. Am Fam Physician. 2014;90(4):244-251.

American Academy of Pediatrics; Committee on Fetus and Newborn. Hospital stay for healthy term newborns. Pediatrics. 2010;125(2):405-409.

Baker RD, Greer FR Committee on Nutrition, American Academy of Pediatrics. Diagnosis and prevention of iron deficiency and iron-deficiency anemia in infants and young children (0–3 years of age). Pediatrics. 2010;126(5):1040-1050.

Mahle WT, Martin GR, Beekman RH, Morrow WR Section on Cardiology and Cardiac Surgery Executive Committee. Endorsement of Health and Human Services recommendation for pulse oximetry screening for critical congenital heart disease. Pediatrics. 2012;129(1):190-192.

American Academy of Pediatrics Newborn Screening Authoring Committee. Newborn screening expands: recommendations for pediatricians and medical homes—implications for the system. Pediatrics. 2008;121(1):192-217.

American Academy of Pediatrics, Joint Committee on Infant Hearing. Year 2007 position statement: principles and guidelines for early hearing detection and intervention programs. Pediatrics. 2007;120(4):898-921.

Maisels MJ, Bhutani VK, Bogen D, Newman TB, Stark AR, Watchko JF. Hyperbilirubinemia in the newborn infant > or = 35 weeks' gestation: an update with clarifications. Pediatrics. 2009;124(4):1193-1198.

Christian CW Committee on Child Abuse and Neglect, American Academy of Pediatrics. The evaluation of suspected child physical abuse [published correction appears in Pediatrics . 2015;136(3):583]. Pediatrics. 2015;135(5):e1337-e1354.

Siu AL, Bibbins-Domingo K, Grossman DC, et al. Screening for autism spectrum disorder in young children: U.S. Preventive Services Task Force recommendation statement. JAMA. 2016;315(7):691-696.

Johnson CP, Myers SM American Academy of Pediatrics Council on Children with Disabilities. Identification and evaluation of children with autism spectrum disorders. Pediatrics. 2007;120(5):1183-1215.

Moyer VA. Prevention of dental caries in children from birth through age 5 years: U.S. Preventive Services Task Force recommendation statement. Pediatrics. 2014;133(6):1102-1111.

Clark MB, Slayton RL American Academy of Pediatrics Section on Oral Health. Fluoride use in caries prevention in the primary care setting. Pediatrics. 2014;134(3):626-633.

Siu AL. Screening for speech and language delay and disorders in children aged 5 years and younger: U.S. Preventive Services Task Force recommendation statement. Pediatrics. 2015;136(2):e474-e481.

Council on Children with Disabilities, Section on Developmental Behavioral Pediatrics, Bright Futures Steering Committee, Medical Home Initiatives for Children with Special Needs Project Advisory Committee. Identifying infants and young children with developmental disorders in the medical home: an algorithm for developmental surveillance and screening [published correction appears in Pediatrics . 2006;118(4):1808–1809]. Pediatrics. 2006;118(1):405-420.

Bibbins-Domingo K, Grossman DC, Curry SJ, et al. Screening for lipid disorders in children and adolescents: U.S. Preventive Services Task Force recommendation statement. JAMA. 2016;316(6):625-633.

National Heart, Lung, and Blood Institute. Expert panel on integrated guidelines for cardiovascular health and risk reduction in children and adolescents. October 2012. https://www.nhlbi.nih.gov/sites/default/files/media/docs/peds_guidelines_full.pdf . Accessed May 9, 2018.

Moyer VA. Screening for primary hypertension in children and adolescents: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2013;159(9):613-619.

Flynn JT, Kaelber DC, Baker-Smith CM, et al. Clinical practice guideline for screening and management of high blood pressure in children and adolescents [published correction appears in Pediatrics . 2017;140(6):e20173035]. Pediatrics. 2017;140(3):e20171904.

Siu AL. Screening for iron deficiency anemia in young children: USPSTF recommendation statement. Pediatrics. 2015;136(4):746-752.

U.S. Preventive Services Task Force. Screening for elevated blood lead levels in children and pregnant women. Pediatrics. 2006;118(6):2514-2518.

Screening Young Children for Lead Poisoning: Guidance for State and Local Public Health Officials . Atlanta, Ga.: U.S. Public Health Service; Centers for Disease Control and Prevention; National Center for Environmental Health; 1997.

O'Connor E, Rossom RC, Henninger M, Groom HC, Burda BU. Primary care screening for and treatment of depression in pregnant and post-partum women: evidence report and systematic review for the U.S. Preventive Services Task Force. JAMA. 2016;315(4):388-406.

Earls MF Committee on Psychosocial Aspects of Child and Family Health, American Academy of Pediatrics. Incorporating recognition and management of perinatal and postpartum depression into pediatric practice. Pediatrics. 2010;126(5):1032-1039.

Siu AL. Screening for depression in children and adolescents: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2016;164(5):360-366.

Weitzman C, Wegner L American Academy of Pediatrics Section on Developmental and Behavioral Pediatrics; Committee on Psychosocial Aspects of Child and Family Health; Council on Early Childhood; Society for Developmental and Behavioral Pediatrics; American Academy of Pediatrics. Promoting optimal development: screening for behavioral and emotional problems [published correction appears in Pediatrics . 2015;135(5):946]. Pediatrics. 2015;135(2):384-395.

Grossman DC, Curry SJ, Owens DK, et al. Vision screening in children aged 6 months to 5 years: U.S. Preventive Services Task Force recommendation statement. JAMA. 2017;318(9):836-844.

Donahue SP, Nixon CN Committee on Practice and Ambulatory Medicine, Section on Ophthalmology, American Academy of Pediatrics; American Association of Certified Orthoptists, American Association for Pediatric Ophthalmology and Strabismus, American Academy of Ophthalmology. Visual system assessment in infants, children, and young adults by pediatricians. Pediatrics. 2016;137(1):28-30.

Lin KW. What to do at well-child visits: the AAFP's perspective. Am Fam Physician. 2015;91(6):362-364.

American Academy of Pediatrics Council on Community Pediatrics. Poverty and child health in the United States. Pediatrics. 2016;137(4):e20160339.

Lavigne JV, Lebailly SA, Hopkins J, Gouze KR, Binns HJ. The prevalence of ADHD, ODD, depression, and anxiety in a community sample of 4-year-olds. J Clin Child Adolesc Psychol. 2009;38(3):315-328.

American Academy of Pediatrics Committee on Practice and Ambulatory Medicine, Section on Ophthalmology, American Association of Certified Orthoptists, American Association for Pediatric Ophthalmology and Strabismus, American Academy of Ophthalmology. Visual system assessment of infants, children, and young adults by pediatricians. Pediatrics. 2016;137(1):28-30.

American Academy of Family Physicians. Clinical preventive service recommendation. Immunizations. http://www.aafp.org/patient-care/clinical-recommendations/all/immunizations.html . Accessed October 5, 2017.

Centers for Disease Control and Prevention. Recommended immunization schedule for children and adolescents aged 18 years or younger, United States, 2018. https://www.cdc.gov/vaccines/schedules/hcp/child-adolescent.html . Accessed May 9, 2018.

National Center for Injury Prevention and Control. 10 leading causes of death by age group, United States—2015. https://www.cdc.gov/injury/images/lc-charts/leading_causes_of_death_age_group_2015_1050w740h.gif . Accessed April 24, 2017.

Durbin DR American Academy of Pediatrics Committee on Injury, Violence, and Poison Prevention. Child passenger safety. Pediatrics. 2011;127(4):788-793.

American Academy of Pediatrics Committee on Injury and Poison Prevention. Reducing the number of deaths and injuries from residential fires. Pediatrics. 2000;105(6):1355-1357.

Gardner HG American Academy of Pediatrics Committee on Injury, Violence, and Poison Prevention. Office-based counseling for unintentional injury prevention. Pediatrics. 2007;119(1):202-206.

American Academy of Pediatrics Committee on Injury, Violence, and Poison Prevention. Prevention of drowning in infants, children, and adolescents. Pediatrics. 2003;112(2):437-439.

American Academy of Pediatrics Committee on Injury and Poison Prevention. Injuries associated with infant walkers. Pediatrics. 2001;108(3):790-792.

American Academy of Pediatrics Committee on Injury and Poison Prevention. Falls from heights: windows, roofs, and balconies. Pediatrics. 2001;107(5):1188-1191.

Dowd MD, Sege RD Council on Injury, Violence, and Poison Prevention Executive Committee; American Academy of Pediatrics. Firearm-related injuries affecting the pediatric population. Pediatrics. 2012;130(5):e1416-e1423.

American Academy of Pediatrics Committee on Injury, Violence, and Poison Prevention. Prevention of choking among children. Pediatrics. 2010;125(3):601-607.

Kendrick D, Young B, Mason-Jones AJ, et al. Home safety education and provision of safety equipment for injury prevention (review). Evid Based Child Health. 2013;8(3):761-939.

American Academy of Pediatrics Section on Oral Health. Maintaining and improving the oral health of young children. Pediatrics. 2014;134(6):1224-1229.

Heyman MB, Abrams SA American Academy of Pediatrics Section on Gastroenterology, Hepatology, and Nutrition Committee on Nutrition. Fruit juice in infants, children, and adolescents: current recommendations. Pediatrics. 2017;139(6):e20170967.

Council on Communications and Media. Media and young minds. Pediatrics. 2016;138(5):e20162591.

Moon RY Task Force on Sudden Infant Death Syndrome. SIDS and other sleep-related infant deaths: evidence base for 2016 updated recommendations for a safe infant sleeping environment. Pediatrics. 2016;138(5):e20162940.

American Academy of Pediatrics Section on Breastfeeding. Breastfeeding and the use of human milk. Pediatrics. 2012;129(3):e827-e841.

Wagner CL, Greer FR American Academy of Pediatrics Section on Breastfeeding; Committee on Nutrition. Prevention of rickets and vitamin D deficiency in infants, children, and adolescents [published correction appears in Pediatrics . 2009;123(1):197]. Pediatrics. 2008;122(5):1142-1152.

Huh SY, Rifas-Shiman SL, Taveras EM, Oken E, Gillman MW. Timing of solid food introduction and risk of obesity in preschool-aged children. Pediatrics. 2011;127(3):e544-e551.

Greer FR, Sicherer SH, Burks AW American Academy of Pediatrics Committee on Nutrition; Section on Allergy and Immunology. Effects of early nutritional interventions on the development of atopic disease in infants and children: the role of maternal dietary restriction, breastfeeding, timing of introduction of complementary foods, and hydrolyzed formulas. Pediatrics. 2008;121(1):183-191.

American Academy of Pediatrics Committee on Nutrition. The use of whole cow's milk in infancy. Pediatrics. 1992;89(6 pt 1):1105-1109.

Fleischer DM, Spergel JM, Assa'ad AH, Pongracic JA. Primary prevention of allergic disease through nutritional interventions. J Allergy Clin Immunol Pract. 2013;1(1):29-36.

Grossman DC, Bibbins-Domingo K, Curry SJ, et al. Screening for obesity in children and adolescents: U.S. Preventive Services Task Force recommendation statement. JAMA. 2017;317(23):2417-2426.

Daniels SR, Hassink SG Committee on Nutrition. The role of the pediatrician in primary prevention of obesity. Pediatrics. 2015;136(1):e275-e292.

American Academy of Family Physicians. Physical activity in children. https://www.aafp.org/about/policies/all/physical-activity.html . Accessed January 1, 2018.

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Mexico Travel Advisory

Travel advisory august 22, 2023, mexico - see state summaries.

Reissued after periodic review with general security updates, and the removal of obsolete COVID-19 page links.

Country Summary: Violent crime – such as homicide, kidnapping, carjacking, and robbery – is widespread and common in Mexico. The U.S. government has limited ability to provide emergency services to U.S. citizens in many areas of Mexico, as travel by U.S. government employees to certain areas is prohibited or restricted. In many states, local emergency services are limited outside the state capital or major cities.

U.S. citizens are advised to adhere to restrictions on U.S. government employee travel. State-specific restrictions are included in the individual state advisories below. U.S. government employees may not travel between cities after dark, may not hail taxis on the street, and must rely on dispatched vehicles, including app-based services like Uber, and regulated taxi stands. U.S. government employees should avoid traveling alone, especially in remote areas. U.S. government employees may not drive from the U.S.-Mexico border to or from the interior parts of Mexico, except daytime travel within Baja California and between Nogales and Hermosillo on Mexican Federal Highway 15D, and between Nuevo Laredo and Monterrey on Highway 85D.

Read the country information page for additional information on travel to Mexico.

Do Not Travel To:

Colima state due to crime and kidnapping .
Guerrero state due to crime .
Michoacan state due to crime and kidnapping .
Sinaloa state due to crime and kidnapping
Tamaulipas state due to crime and kidnapping.
Zacatecas state due to crime and kidnapping .

Reconsider Travel To:

Baja California state due to crime and kidnapping .
Chihuahua state due to crime and kidnapping .
Durango state due to crime .
Guanajuato state due to crime and kidnapping .
Jalisco state due to crime and kidnapping .
Morelos state due to crime .
Sonora state due to crime and kidnapping .

Exercise Increased Caution When Traveling To:

Aguascalientes state due to crime .
Baja California Sur state due to crime .
Chiapas state due to crime .
Coahuila state due to crime .
Hidalgo state due to crime .
Mexico City due to crime .
Mexico State due to crime .
Nayarit state due to crime.
Nuevo Leon state due to crime and kidnapping .
Oaxaca state due to crime .
Puebla state due to crime and kidnapping .
Queretaro state due to crime .
Quintana Roo state due to crime .
San Luis Potosi state due to crime and kidnapping .
Tabasco state due to crime .
Tlaxcala state due to crime .
Veracruz state due to crime .

Exercise Normal Precautions When Traveling To:

Campeche state
Yucatan state

Visit our website for Travel to High-Risk Areas .

If you decide to travel to Mexico:

Keep traveling companions and family back home informed of your travel plans. If separating from your travel group, send a friend your GPS location. If taking a taxi alone, take a photo of the taxi number and/or license plate and text it to a friend.
Use toll roads when possible and avoid driving alone or at night. In many states, police presence and emergency services are extremely limited outside the state capital or major cities.
Exercise increased caution when visiting local bars, nightclubs, and casinos.
Do not display signs of wealth, such as wearing expensive watches or jewelry.
Be extra vigilant when visiting banks or ATMs.
Enroll in the Smart Traveler Enrollment Program (STEP) to receive Alerts and make it easier to locate you in an emergency.
Follow the Department of State on Facebook and Twitter .
Follow the U.S. Embassy on Facebook and Twitter .
Review the Country Security Report for Mexico.
Mariners planning travel to Mexico should check for U.S. maritime advisories and alerts , which include instructions on reporting suspicious activities and attacks to Mexican naval authorities.
Prepare a contingency plan for emergency situations. Review the Traveler’s Checklist .
Visit the CDC page for the latest travel health information related to your travel.

Aguascalientes state – Exercise Increased Caution

Exercise increased caution due to crime.

Criminal activity and violence may occur throughout the state.

There are no restrictions on travel for U.S. government employees in Aguascalientes state.

Baja California state – Reconsider Travel

Reconsider travel due to crime and kidnapping.

Transnational criminal organizations compete in the border area to establish narco-trafficking and human smuggling routes. Violent crime and gang activity are common. Travelers should remain on main highways and avoid remote locations. Of particular concern is the high number of homicides in the non-tourist areas of Tijuana. Most homicides appeared to be targeted; however, criminal organization assassinations and territorial disputes can result in bystanders being injured or killed. U.S. citizens and LPRs have been victims of kidnapping.

U.S. government employees must adhere to the noted restrictions:

Mexicali Valley: U.S. government employees should avoid the Mexicali Valley due to the heightened possibility of violence between rival cartel factions. The boundaries of the restricted area are: to the east, the Baja California/Arizona and Baja California/Sonora borders; to the south, from La Ventana (on Highway 5) due east to the Colorado River; to the west, Highway 5; and to the north, Boulevard Lazaro Cardenas/Highway 92/Highway 1 to Carretera Aeropuerto, from the intersection of Highway 1 and Carretera Aeropuerto due north to the Baja California/California border, and from that point eastward along the Baja California/California border.
Travelers may use Highways 2 and 2D to transit between Mexicali, Los Algodones, and San Luis Rio Colorado during daylight hours. Travelers may also use Highways 1 and 8 to transit to and from the Mexicali Airport during daylight hours. Travel on Highway 5 is permissible during daylight hours.

There are no other travel restrictions for U.S. government employees in Baja California state. These include high-traffic tourism areas of border and coastal communities, such as Tijuana , Ensenada , and Rosarito .

Baja California Sur state – Exercise Increased Caution

There are no restrictions on travel for U.S. government employees in Baja California Sur state.

Campeche state – Exercise Normal Precautions

Exercise normal precautions.

There are no restrictions on travel for U.S. government employees in Campeche state.

Chiapas state – Exercise Increased Caution

There are no restrictions on travel for U.S. government employees in Chiapas state.

Chihuahua state – Reconsider Travel

Violent crime and gang activity are common. Most homicides are targeted assassinations against members of criminal organizations. Battles for territory between criminal groups have resulted in violent crime in areas frequented by U.S. citizens and U.S. government employees, including restaurants and malls during daylight hours. Bystanders have been injured or killed in shooting incidents. U.S. citizens and LPRs have been victims of kidnapping.

U.S. government employee travel is limited to the following areas with the noted restrictions:

Ciudad Juarez: U.S. government employees may travel to the area of Ciudad Juarez bounded to the east by Bulevar Independencia; to the south by De los Montes Urales/Avenida Manuel J Clouthier/Carretera de Juárez; to the west by Via Juan Gabriel/Avenida de los Insurgentes/Calle Miguel Ahumada/Francisco Javier Mina/Melchor Ocampo; and to the north by the U.S.-Mexico border. Direct travel to the Ciudad Juarez airport (officially called the Abraham González International Airport) and the factories located along Bulevar Independencia and Las Torres is permitted. Travel to San Jerónimo is permitted only through the United States via the Santa Teresa U.S. Port of Entry; travel via Anapra is prohibited.

U.S. government employees may only travel from Ciudad Juarez to the city of Chihuahua during daylight hours via Federal Highway 45, with stops permitted only at the Guardia Nacional División Caminos station, the Umbral del Milenio overlook area, the border inspection station at KM 35, and the shops and restaurants on Federal Highway 45 in the city of Ahumada.

U.S. government employees may travel between Ciudad Juarez and Ascension via Highway 2.
Nuevo Casas Grandes Area (including Nuevo Casas Grandes, Casas Grandes, Mata Ortiz, Colonia Juárez, Colonia LeBaron, Paquimé and San Buenaventura): U.S. government employees may travel to the Nuevo Casas Grandes area during daylight hours via Mexico Federal Highway 2, and subsequently Federal Highway 10, to Nuevo Casas Grandes. Employees are permitted to stay overnight in the cities of Nuevo Casas Grandes and Casas Grandes only.
City of Chihuahua: U.S. government employees may travel at any time to the area of the city of Chihuahua bounded to the north by Avenida Transformación; to the east by Avenida Tecnológico/Manuel Gómez Morín/Highway 16/Blvd.José Fuentes Mares; to the west by the city boundary; and to the south by Periférico Francisco R. Almada.
U.S. government employees may travel on Highways 45, 16, and 45D through the city of Chihuahua and to the Chihuahua airport (officially called the General Roberto Fierro Villalobos International Airport).
U.S. government employees may travel to Santa Eulalia to the east of the city of Chihuahua, as well as to Juan Aldama via Highway 16 to the northeast.
U.S. government employees may travel south of the city of Chihuahua on Highway 45 to the southern boundary of Parral, including each town directly connected to Highway 45, including Lázaro Cárdenas, Pedro Meoqui, Santa Cruz de Rosales, Delicias, Camargo, Ciudad Jiménez, and Parral itself.
U.S. government employees may only travel on official business from the city of Chihuahua on Highway 16 to Ciudad Cuauhtémoc bounded by Highway 21 to the north and east, Highway 5 to the west, and Bulevar Jorge Castillo Cabrera to the south.
Ojinaga: U.S. government employees must travel to Ojinaga via U.S. Highway 67 and enter through the U.S. Port of Entry in Presidio, Texas.
Palomas: U.S. government employees may travel to Palomas via U.S. highways through the U.S. Port of Entry in Columbus, New Mexico, or via Highway 2 in Mexico.

U.S. government employees may not travel to other areas of Chihuahua, including Copper Canyon .

Coahuila state – Exercise Increased Caution

Violent crime and gang activity occur in parts of Coahuila state.

U.S. government employees must adhere to the following travel restrictions:

Zaragoza, Morelos, Allende, Nava, Jimenez, Villa Union, Guerrero, and Hidalgo municipalities : U.S. government employees may not travel to these municipalities.
Piedras Negras and Ciudad Acuña: U.S. government employees must travel directly from the United States and observe a curfew from midnight to 6:00 a.m. in both cities.

There are no other restrictions on travel for U.S. government employees in Coahuila state.

Colima state – Do Not Travel

Do not travel due to crime and kidnapping.

Violent crime and gang activity are widespread. Most homicides are targeted assassinations against members of criminal organizations. Shooting incidents between criminal groups have injured or killed bystanders. U.S. citizens and LPRs have been victims of kidnapping.

Travel for U.S. government employees is limited to the following areas with noted restrictions:

Manzanillo: U.S. government employee travel is limited to the tourist and port areas of Manzanillo.
Employees traveling to Manzanillo from Guadalajara must use Federal Toll Road 54D during daylight hours.

U.S. government employees may not travel to other areas of Colima state.

Durango state – Reconsider Travel

Reconsider travel due to crime.

Violent crime and gang activity are common in parts of Durango state.

West and south of Federal Highway 45: U.S. government employees may not travel to this region of Durango state.

There are no other restrictions on travel for U.S. government employees in Durango state.

Guanajuato state – Reconsider Travel

Gang violence, often associated with the theft of petroleum and natural gas from the state oil company and other suppliers, occurs in Guanajuato, primarily in the south and central areas of the state. Of particular concern is the high number of murders in the southern region of the state associated with cartel-related violence. U.S. citizens and LPRs have been victims of kidnapping.

Areas south of Federal Highway 45D: U.S. government employees may not travel to the area south of and including Federal Highway 45D, Celaya, Salamanca, and Irapuato.

There are no other restrictions on travel for U.S. government employees in Guanajuato state, which includes tourist areas in: San Miguel de Allende , Guanajuato City , and surrounding areas.

Guerrero state – Do Not Travel

Do not travel due to crime.

Crime and violence are widespread. Armed groups operate independently of the government in many areas of Guerrero. Members of these groups frequently maintain roadblocks and may use violence towards travelers. U.S. citizens and LPRs have been victims of kidnapping in previous years.

Travel for U.S. government employees is limited to the following area with the noted restrictions:

Taxco: U.S. government employees must use Federal Highway 95D, which passes through Cuernavaca, Morelos, and stay within downtown tourist areas of Taxco. Employees may visit Grutas de Cacahuamilpa National Park during the day with a licensed tour operator.

U.S. government employees may not travel to other areas of the state of Guerrero, including to tourist areas in Acapulco , Zihuatanejo , and Ixtapa .

Hidalgo state – Exercise Increased Caution

There are no restrictions on travel for U.S. government employees in Hidalgo state.

Jalisco state – Reconsider Travel

Violent crime and gang activity are common in parts of Jalisco state. In Guadalajara, territorial battles between criminal groups take place in tourist areas. Shooting incidents between criminal groups have injured or killed innocent bystanders. U.S. citizens and LPRs have been victims of kidnapping.

Jalisco-Michoacan border and Federal Highway 110: U.S. government employees may not travel to the area between Federal Highway 110 and the Jalisco-Michoacan border, nor travel on Federal Highway 110 between Tuxpan, Jalisco, and the Michoacan border.
Federal Highway 80: U.S. government employees may not travel on Federal Highway 80 south of Cocula.

There are no other restrictions on travel for U.S government employees in Jalisco state which includes tourist areas in: Guadalajara Metropolitan Area , Puerto Vallarta (including neighboring Riviera Nayarit) , Chapala , and Ajijic .

Mexico City (Ciudad de Mexico) – Exercise Increased Caution

Both violent and non-violent crime occur throughout Mexico City. Use additional caution, particularly at night, outside of the frequented tourist areas where police and security patrol more routinely. Petty crime occurs frequently in both tourist and non-tourist areas.

There are no restrictions on travel for U.S. government employees in Mexico City.

Mexico State (Estado de Mexico) – Exercise Increased Caution

Both violent and non-violent crime occur throughout Mexico State. Use additional caution in areas outside of the frequented tourist areas, although petty crime occurs frequently in tourist areas as well.

There are no restrictions on travel for U.S. government employees in Mexico State.

Michoacan state – Do Not Travel

Do not travel due to crime and kidnapping.

Crime and violence are widespread in Michoacan state. U.S. citizens and LPRs have been victims of kidnapping.

Travel for U.S. government employees is limited to the following areas with the noted restrictions:

Federal Highway 15D: U.S. government employees may travel on Federal Highway 15D to transit the state between Mexico City and Guadalajara.
Morelia: U.S. government employees may travel by air and by land using Federal Highways 43 or 48D from Federal Highway 15D.
Lazaro Cardenas: U.S. government employees must travel by air only and limit activities to the city center or port areas.

U.S. government employees may not travel to other areas of the state of Michoacan, including the portions of the Monarch Butterfly Reserve located in Michoacan.

Morelos state – Reconsider Travel

Violent crime and gang activity are common in parts of Morelos state.

There are no restrictions on travel for U.S. government employees in Morelos state.

Nayarit state – Exercise Increased Caution

Criminal activity and violence may occur throughout Nayarit state.

There are no restrictions on travel for U.S government employees in Nayarit state.

Nuevo Leon state – Exercise Increased Caution

Exercise increased caution due to crime and kidnapping.

Criminal activity and violence may occur throughout the state. U.S. citizens and LPRs have been victims of kidnapping.

There are no restrictions on travel for U.S. government employees in Nuevo Leon state.

Oaxaca state – Exercise Increased Caution

Criminal activity and violence occur throughout the state.

U.S. travelers are reminded that U.S. government employees must adhere to the following travel restrictions:

Isthmus region: U.S. government employees may not travel to the area of Oaxaca bounded by Federal Highway 185D to the west, Federal Highway 190 to the north, and the Oaxaca-Chiapas border to the east. This includes the cities of Juchitan de Zaragoza, Salina Cruz, and San Blas Atempa.
Federal Highway 200 northwest of Pinotepa: U.S. government employees may not use Federal Highway 200 between Pinotepa and the Oaxaca-Guerrero border.

There are no restrictions on travel for U.S. government employees to other parts of Oaxaca state, which include tourist areas in: Oaxaca City , Monte Alban , Puerto Escondido, and Huatulco .

Puebla state – Exercise Increased Caution

There are no restrictions on travel for U.S. government employees in Puebla state.

Queretaro state – Exercise Increased Caution

There are no restrictions on travel for U.S. government employees in Queretaro state.

Quintana Roo state – Exercise Increased Caution

Criminal activity and violence may occur in any location, at any time, including in popular tourist destinations. Travelers should maintain a high level of situational awareness, avoid areas where illicit activities occur, and promptly depart from potentially dangerous situations.

While not directed at tourists, shootings between rival gangs have injured innocent bystanders. Additionally, U.S. citizens have been the victims of both non-violent and violent crimes in tourist and non-tourist areas.

There are no restrictions on travel for U.S. government employees in Quintana Roo state. However, personnel are advised to exercise increased situational awareness after dark in downtown areas of Cancun, Tulum, and Playa del Carmen, and to remain in well-lit pedestrian streets and tourist zones.

San Luis Potosi state – Exercise Increased Caution

Criminal activity and violence may occur throughout the state. U.S. citizens and LPRs have been victims of kidnapping.

There are no restrictions on travel for U.S. government employees in San Luis Potosi state.

Sinaloa state – Do Not Travel

Violent crime is widespread. Criminal organizations are based in and operating in Sinaloa. U.S. citizens and LPRs have been victims of kidnapping.

Mazatlan: U.S. government employees may travel to Mazatlan by air or sea only, are limited to the Zona Dorada and historic town center, and must travel via direct routes between these destinations and the airport and sea terminal.
Los Mochis and Topolobampo: U.S. government employees may travel to Los Mochis and Topolobampo by air or sea only, are restricted to the city and the port, and must travel via direct routes between these destinations and the airport.

U.S. government employees may not travel to other areas of Sinaloa state.

Sonora state – Reconsider Travel

Sonora is a key location used by the international drug trade and human trafficking networks. Violent crime is widespread. U.S. citizens and LPRs have been victims of kidnapping. Travelers should maintain a heightened level of awareness of their surroundings in all their travels in Sonora. Security incidents may occur in any area of Sonora.

Travel between Hermosillo and Nogales: U.S. government employees may travel between the U.S. Ports of Entry in Nogales and Hermosillo during daylight hours via Federal Highway 15 only. U.S. government employees may not use ANY taxi services, public buses, nor ride-share applications due to a lack of secure vetting and/or dispatching procedures. Travelers should exercise caution and avoid unnecessary stops as security incidents, including sporadic, armed carjackings, and shootings have been reported along this highway during daylight hours. Travelers should have a full tank of gas and inform friends or family members of their planned travel.
Nogales: U.S. government employees may not travel in the triangular area north of Avenida Tecnologico, west of Bulevar Luis Donaldo Colosio (Periferico), nor east of Federal Highway 15D (Corredor Fiscal). U.S. government employees also may not travel in the residential and business areas to east of the railroad tracks along Plutarco Elias Calle (HWY 15) and Calle Ruiz Cortino, including the business area around the Morley pedestrian gate port-of-entry. U.S. government employees may not use ANY taxi services, public buses, nor ride-share applications in Nogales due to a lack of secure vetting and/or dispatching procedures and the danger of kidnapping and other violent crimes. 
Puerto Peñasco: U.S. government employees may travel between Puerto Peñasco and the Lukeville-Sonoyta U.S. Port of Entry during daylight hours via Federal Highway 8 only. They may not travel on any other route to Puerto Peñasco. U.S. government employees may not use ANY taxi services, public buses, nor ride-share applications in Puerto Peñasco. due to a lack of secure vetting and/or dispatching procedures and the danger of kidnapping and other violent crimes.
Triangular region near Mariposa U.S. Port of Entry: U.S. government employees may not travel into or through the triangular region west of the Mariposa U.S. Port of Entry, east of Sonoyta, and north of Altar municipality.
San Luis Rio Colorado, Cananea, and Agua Prieta : U.S. government employees may travel directly from the nearest U.S. Port of Entry to San Luis Rio Colorado, Cananea (via Douglas Port of Entry), and Agua Prieta, but may not go beyond the city limits. Travel is limited to daylight hours only. Travel between Nogales and Cananea via Imuris is not permitted. U.S. government employees may not use ANY taxi services, public buses, nor ride-share applications in these cities due to a lack of secure vetting and/or dispatching procedures and the danger of kidnapping and other violent crimes.
Eastern and southern Sonora (including San Carlos Nuevo Guaymas and Alamos): U.S. government employees may not travel to areas of Sonora east of Federal Highway 17, the road between Moctezuma and Sahuaripa, and State Highway 20 between Sahuaripa and the intersection with Federal Highway 16. U.S. government employees may travel to San Carlos Nuevo Guaymas and Alamos; travel to Alamos is only permitted by air and within city limits. U.S. government employees may not travel to areas of Sonora south of Federal Highway 16 and east of Federal Highway 15 (south of Hermosillo), as well as all points south of Guaymas, including Empalme, Guaymas, Obregon, and Navojoa. U.S. government employees may not use ANY taxi services, public buses, nor ride-share applications in these areas due to a lack of secure vetting and/or dispatching procedures and the danger of kidnapping and other violent crimes.

U.S. government employees may travel to other parts of Sonora state in compliance with the above restrictions, including tourist areas in: Hermosillo , Bahia de Kino , and Puerto Penasco .

Tabasco state – Exercise Increased Caution

There are no restrictions on travel for U.S. government employees in Tabasco state.

Tamaulipas state – Do Not Travel

Organized crime activity – including gun battles, murder, armed robbery, carjacking, kidnapping, forced disappearances, extortion, and sexual assault – is common along the northern border and in Ciudad Victoria. Criminal groups target public and private passenger buses, as well as private automobiles traveling through Tamaulipas, often taking passengers and demanding ransom payments.

Heavily armed members of criminal groups often patrol areas of the state and operate with impunity particularly along the border region from Reynosa to Nuevo Laredo. In these areas, local law enforcement has limited capacity to respond to incidents of crime. Law enforcement capacity is greater in the tri-city area of Tampico, Ciudad Madero, and Altamira, which has a lower rate of violent criminal activity compared to the rest of the state.

U.S. citizens and LPRs have been victims of kidnapping.

Matamoros and Nuevo Laredo: U.S. government employees may only travel within a limited radius around and between the U.S. Consulates in Nuevo Laredo and Matamoros, their homes, the respective U.S. Ports of Entry, and limited downtown sites, subject to an overnight curfew.
Overland travel in Tamaulipas: U.S. government employees may not travel between cities in Tamaulipas using interior Mexican highways. Travel between Nuevo Laredo and Monterrey is limited to Federal Highway 85D during daylight hours with prior authorization.

U.S. government employees may not travel to other parts of Tamaulipas state.

Tlaxcala state – Exercise Increased Caution

There are no restrictions on travel for U.S. government employees in Tlaxcala state.

Veracruz state – Exercise Increased Caution

Violent crime and gang activity occur with increasing frequency in Veracruz, particularly in the center and south near Cordoba and Coatzacoalcos. While most gang-related violence is targeted, violence perpetrated by criminal organizations can affect bystanders. Impromptu roadblocks requiring payment to pass are common.

There are no restrictions on travel for U.S. government employees in Veracruz state.

Yucatan state – Exercise Normal Precautions

There are no restrictions on travel for U.S. government employees in Yucatan state, which include tourist areas in: Chichen Itza , Merida , Uxmal , and Valladolid .

Zacatecas state – Do Not Travel

Violent crime, extortion, and gang activity are widespread in Zacatecas state. U.S. citizens and LPRs have been victims of kidnapping.

Zacatecas City : U.S. government employee travel is limited to Zacatecas City proper, and employees may not travel overland to Zacatecas City.
U.S. government employees may not travel to other areas of Zacatecas state.

Travel Advisory Levels

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Ventilation in Buildings

Summary of recent changes.

Added Key Strategies, a simplified summary of the most important recommendations on this page.
Added discussion on “How much ventilation is enough?” with a recommendation to get at least 5 air changes per hour of clean air in occupied spaces.
Updated the minimum filter recommendation to Minimum Efficiency Reporting Value (MERV) 13.
Updated the guidance on post-occupancy flushing of building air.
Included more information on up-front, maintenance, and energy cost considerations for ventilation strategies.
Added a Frequently Asked Question on “Do-It-Yourself (DIY) Air Cleaners.”
Updated all Frequently Asked Questions to include a concise answer, followed by more detail.
Updated the discussion on Whole-Room Ultraviolet Germicidal Irradiation (also called Far UV) in Frequently Asked Question #7 .

View Previous Changes

Definition of Ventilation

What You Need to Know

Ventilation mitigation strategies, how much ventilation is enough, ventilation frequently asked questions, ventilation.

Ventilation is a term with different meanings to different people. For the purpose of this webpage, “ventilation” includes:

Indoor air movement and dilution of viral particles through mechanical or nonmechanical (also called natural) means.
Filtration through central heating, ventilation and air conditioning (HVAC) systems and/or in-room air cleaners (portable or permanently mounted).*
Air treatment with Ultraviolet Germicidal Irradiation (UVGI) systems (also called Germicidal Ultraviolet or GUV).*

* These air cleaning techniques are sometimes referred to as “equivalent ventilation.” They are not a substitute for meeting minimum outdoor air delivery requirements that may be specified in national, state, and local building codes.

An important principle to remember when contemplating mitigation strategies is to “First do no harm.” Building owners and operators should strongly consider seeking expert consultation when considering mitigation strategies if they lack knowledge and experience in implementing those strategies.
Airborne viral particles spread between people more readily indoors than outdoors. Indoors, the concentration of viral particles is often higher than outdoors. Protective indoor ventilation practices can reduce the airborne viral concentrations and the overall viral exposure to occupants.
Ventilation system upgrades or improvements can increase the delivery of clean air and dilute potential contaminants. Buildings that provided healthy, code-compliant indoor air quality prior to the pandemic can be improved for pandemic and post-pandemic occupancy using less costly interventions.
While the mitigation strategies can be universally applied across many indoor environments, applying them to different building types, occupancies, and activities under environmental and seasonal changes can be challenging. The building owner or operator should identify which strategies are appropriate for each building throughout the year.
Implementing multiple building-level mitigation strategies at the same time is consistent with CDC’s layered approach and will increase overall effectiveness of ventilation interventions.
Building owners and operators can participate in the Clean Air in Building Challenge to improve indoor air quality and protect public health.
Get answers to Frequently Asked Questions below about ventilation and safe building practices during and after the COVID-19 pandemic.

When indoors, ventilation mitigation strategies can help reduce viral particle concentration. The lower the concentration, the less likely viral particles can be inhaled into the lungs (potentially lowering the inhaled dose); contact eyes, nose, and mouth; or fall out of the air to accumulate on surfaces. Although it isn’t known exactly how much the concentration of viral particles in air needs to be reduced to start reducing risk of viral infection, ventilation mitigation strategies still provide a reasonable approach to reducing risk. Not all interventions will work in all scenarios and their selection must be carefully evaluated prior to adoption.

These ventilation interventions can reduce the spread of disease, but they will not eliminate risk completely. These interventions are intended to lower transmission risk by lowering the concentration of infectious aerosols in a room. However, the overall transmission reduction is less likely to apply to people who are very close (e.g. face-to-face) to the infectious source. Some of the following interventions are based on COVID-19 Technical Resources published by ASHRAE (a professional organization formerly known as the American Society of Heating, Refrigerating, and Air Conditioning Engineers).

The Clean Air in Buildings Challenge is a national call to action that highlights a range of recommendations and resources available to assist with reducing risks from airborne viruses and other indoor contaminants. Create your clean indoor air action plan today.

In addition to buildings, vehicles – including public transportation such as buses, subways, trains, school buses, carpools, and rideshares – are also areas where ventilation improvements can be applied to reduce the spread of airborne viruses and lower the risk of exposure.

The recommendations presented here are not intended to replace guidance that may already exist in national, state, and local standards and guidelines. For example, some healthcare spaces have specified ventilation requirements intended to prevent and control infectious diseases. For spaces where existing standards and guidelines specify lower ventilation rates than the recommendations presented here, building owners and managers are encouraged to consider adoption of the more protective guidance.

Important: For interventions listed below that are marked with “**,” consulting with professionals experienced in the proper selection, implementation, and commissioning of HVAC improvements is strongly encouraged. Their experience should preferably include the building, system, and occupancy types under evaluation. Other interventions may require similar consultation, depending upon the knowledge and experience of the individuals responsible for implementing changes to the building.

Improving Air Circulation

Applicable codes are based on the year of building construction or latest renovation and intended building occupancy.
Preferably, upgrade HVAC system performance to meet current ventilation code requirements at current occupancy levels.**
This will develop a strong and lasting baseline upon which further interventions can be implemented.

This measure will potentially increase energy costs. Use of an energy recovery ventilator (ERV) can lessen the potential energy and system implications of increased outdoor air.

Open the outdoor air dampers on your HVAC equipment beyond minimum settings to reduce or eliminate HVAC air recirculation. In mild weather, this will not affect thermal comfort or indoor humidity. However, this may be difficult to do in cold, hot, or humid weather.**
Open windows and doors, when weather conditions allow, to increase outdoor air flow. Even a slightly open window can introduce beneficial outdoor air.
Do not open windows and doors if doing so poses a safety or health risk (e.g., risk of falling, triggering asthma symptoms) to building occupants. Use caution in highly polluted areas when increasing outdoor air ventilation.
To safely achieve this, fan placement is important and will vary based on room configuration.
Avoid placing fans in a way that could potentially cause contaminated air to flow directly from one person to another ( see FAQ #11 below on indoor use of fans).
One helpful strategy is to use a window fan, placed safely and securely in a window, to exhaust room air to the outdoors. This will help draw outdoor air into the room via other open windows and doors without generating strong room air currents. Similar results can be established in larger facilities using other fan systems, such as gable fans and roof ventilators.
Increase total airflow to increase room air mixing and reduce viral particle concentration and subsequent exposure potential.**
Turn off any demand-controlled ventilation (DCV) controls that reduce air supply based on occupancy or temperature during occupied hours.**
In homes and buildings where the HVAC fan operation can be controlled at the thermostat, set the fan to the “on” position instead of “auto,” which will operate the fan continuously, even when heating or air conditioning is not required.
Ensure restroom exhaust fans are functional and operating at full capacity when the building is occupied.
Inspect and maintain exhaust ventilation systems in areas such as kitchens, cooking areas, etc. Operate these systems any time these spaces are occupied. Operating them even when the specific space is not occupied will increase overall ventilation within the occupied building.
In non-residential settings where an infectious source was not known to have been present, run the HVAC system at maximum outside airflow for 2 hours, or until the building has achieved at least 3 air changes, after the building is no longer occupied. If an infectious source was present, see FAQ #2 .
Generate clean-to-less-clean air movement by evaluating and repositioning as necessary, the supply louvers, exhaust air grilles, and/or damper settings.** See FAQ #4 below on Directional Airflow. This recommendation is easier to accomplish when the supply and exhaust points are included as part of a “drop ceiling.”

Improving Air Cleanliness

Ensure ventilation systems operate properly and are up to date on maintenance.
Make sure air filters are properly sized and within their recommended service life.
Inspect filter housing and racks to ensure appropriate filter fit and minimize air that flows around, instead of through, the filter.
Use HEPA systems to enhance air cleaning (especially in higher risk areas such as a medical office or areas frequently inhabited by people with a higher likelihood of having COVID-19 and/or an increased risk of getting COVID-19). See FAQ #5 below on HEPA filters and in-room HEPA air cleaners.
In-room air cleaners that use filters less efficient than HEPA filters also exist and can contribute to room air cleaning. However, they should be clearly labeled as non-HEPA units.
Some air cleaners/air purifiers use technologies other than filtration. See FAQ #8 for a detailed discussion of factors to consider before using these other technologies.
Upper-room UVGI systems can be used to provide air treatment within occupied spaces.
In-duct UVGI systems can help enhance air cleaning inside central ventilation systems.
See detailed discussion in FAQs #6 and #7 .

Aim for 5 Air Changes per Hour (ACH)

When possible, aim for 5 or more air changes per hour (ACH) of clean air to help reduce the number of germs in the air.

This can be achieved through any combination of central ventilation system, natural ventilation, or additional devices that provide equivalent ACH (eACH † ) to your existing ventilation. Supplying or exhausting an amount of air (use the larger of the two values but do not add them together) that is equal to all the air in a space is called an air change. Multiplying that amount by 5 and delivering it over one hour results in 5 ACH.

To calculate the ACH (or eACH):

Determine (or measure) the airflow through the system in cubic feet per minute (cfm).
Determine the area of the room = length (ft) x width (ft)
Determine the height of the room (ft).
Calculate ACH:

ACH = cfm × 60 Area × Height

When multiple strategies are used, repeat the ACH calculation for each system then add together for a total ACH value (which could be compared to the minimum 5 ACH recommendation).

Note: See FAQ #2 and FAQ #5 for examples on how the ACH calculation may be applied.

While there is insufficient science to identify an optimum ventilation strategy for all spaces, 5 ACH is what portable air cleaners provide (as eACH) when properly sized following the Environmental Protection Agency’s guidance [2.9 MB, 7 pages] on the selection of portable air cleaners. Five ACH will not guarantee totally safe air in any space, but it reduces the risk of exposure to germs and other harmful air contaminants.

Rather than a hard-and-fast rule, the 5 ACH target provides a rough guide to air change levels likely to be helpful in reducing infectious particles. For example, increasing ventilation from 2 to 5 ACH substantially reduces the time to remove airborne contaminants.

Large volume spaces with very few occupants (e.g., a warehouse) may not require 5 ACH and spaces with high occupancy or higher-risk occupants may need higher than 5 ACH.
While ACH levels higher than 5 (e.g., those used in airborne isolation rooms in hospitals) may reduce infectious aerosols further, the potential benefits of increased ventilation should be balanced with the additional upfront, periodic maintenance, and energy costs that may be incurred.
Some limited studies have demonstrated this protective benefit of increased ACH, although an optimum number remains uncertain.
A Lancet Commission Report [249 KB, 33 pages] that draws on available scientific evidence proposes ACH levels of 4 as “Good,” 6 as “Better,” and >6 as “Best,” underscoring that ACH (to include eACH) represents a continuum.
It is unknown exactly how much this will reduce the risk of getting a viral infection in an indoor space.
However, the improvements are reasonable for indoor environments when additional protection is desired. More research is needed to evaluate the influence of central ventilation, portable air cleaning, and UV air treatment on respiratory infectious disease transmission.

† Some air cleaning and air treatment devices do not bring in outdoor air. Instead, they clean or treat the indoor air to reduce the concentration of infectious particles. Thus, they give eACH without the need or expense of conditioning outdoor air. Note that eACH depends on the contaminant. An air treatment device that provides eACH for particles may not be effective against other contaminants such as gases and vapors.

Cost Considerations

The ventilation interventions listed above come with a range of initial costs and operating costs, which, along with risk assessment factors – such as community incidence rates and the adoption of other interventions – may affect the selection of ventilation mitigation strategies. The following are examples of cost estimates for different strategies:

Intervention Strategy

Up-front Cost

Ongoing Daily Interaction

Ongoing Maintenance Requirements and Incremental Energy Usage

Opening windows

No ongoing maintenance requirements
Incremental energy usage varies, depending on ambient outdoor conditions

Expanded operation of dedicated exhaust ventilation

Periodic preventive maintenance required
Incremental energy usage varies, depending on exhaust system capacity and ambient outdoor conditions

Repositioning HVAC outdoor air dampers

Incremental energy usage varies, depending on HVAC system capacity and ambient outdoor conditions

Switching thermostats from “Auto” to “On” or adjusting building HVAC control systems to disable Demand Controlled Ventilation (DCV)

Incremental energy usage varies, depending upon fan energy consumption

Using fans to increase effectiveness of open windows

Repositioning supply/exhaust diffusers to create directional airflow

No incremental energy usage

Adding in-room HEPA fan/filter systems

$500 (approximately)

Must inspect/replace HEPA filter per manufacturer instructions
Low incremental energy usage

Adding upper room UVGI

[Typical classroom requires 2-3 fixtures]

< $1500 (approx. per fixture)

No (unless manual activation)

Must clean/inspect/replace UVGI lamps per manufacturer instructions

Adding in-duct UVGI to treat moving air

Varied, more cost-effective (<$0.25/cfm) with larger systems

Some SARS-CoV-2 viral particles might travel from one space to another through an HVAC system. However, this is not known to be a significant risk for disease transmission.

While airflow distribution within an occupied space is an important factor worth evaluation (see FAQ #11 ), outbreak investigations have predominantly found that COVID-19 transmission occurs between an infected person and uninfected persons in the same space. Viral RNA has reportedly been found on return air grilles, in return air ducts, and on heating, ventilation, and air conditioning (HVAC) filters, but detecting viral RNA alone does not imply that the virus was capable of transmitting disease. One research group reported that the use of a new air-sampling method allowed them to find viable viral particles within a COVID-19 patient’s hospital room with good ventilation, filtration and ultraviolet (UV) treatment (at distances as far as 16 feet from the patient). However, the concentration of viable virus detected was believed to be too low to cause disease transmission. There may be some implications for HVAC systems associated with these findings, but it is too early to conclude that with certainty. While airflows within a particular space may help spread disease among people in that space, there is no definitive evidence to date that viable virus has been transmitted through an HVAC system to result in disease transmission to people in other spaces served by the same system.

Healthcare facilities have ventilation requirements in place to help prevent and control infectious diseases that are associated with some healthcare environments. For more information, see the CDC Guidelines for Environmental Infection Control in Health-Care Facilities .

Non-healthcare (e.g., businesses and schools) building owners and managers should, at a minimum, maintain building ventilation systems according to state and local building codes and applicable guidelines. Ensuring appropriate outdoor air and ventilation rates is a practical step to ensure good indoor air quality. However, these codes do not address infection prevention in non-healthcare buildings and code minimum ventilation may be insufficient to protect indoor occupants under some circumstances (e.g., high incidence rates, occupants near one another, crowded spaces, etc.).

The time required for dilution will depend on room ventilation airflow and its effectiveness.

While large droplets (100 micrometers [µm] and larger) will settle to surrounding surfaces within seconds, smaller particles can stay suspended in the air for much longer. It can take several minutes for particles 10 µm in size to settle, while particles 5 µm and smaller may not settle for hours or even days. Dilution ventilation and particle filtration are commonly used to remove these smaller particles from the air. Larger particles can also be removed using these strategies, but since they fall out of the air quickly, they might not have a chance to get captured by filtration systems.

Delivering (or exhausting) an amount of air that is equal to a room’s volume is called an “air change.” Delivering this amount of air over a 60-minute period is called an “air change per hour” (ACH). The time required to remove airborne particles from a space can be estimated using Table B.1 in the CDC’s Guidelines for Environmental Infection Control in Health-Care Facilities (2003). The estimates assume the source of infectious particles is no longer present in the space. The estimates in the table are based upon the rate that particle-free air is delivered to the room and the desired removal efficiency (99% or 99.9%). The particle-free air, measured in air changes per hour (ACH), can be uncontaminated supply air or the clean exhaust from a High Efficiency Particulate Air (HEPA) fan/filtration system [See HEPA filtration discussion below].

Although there are some highly contagious airborne diseases (like measles) where CDC provides specific guidance for 99.9% clearance wait times, the general recommendation in CDC’s Guidelines for Environmental Infection Control in Health-Care Facilities is to wait to allow for a 99% reduction of any generated airborne particles before re-entering the room.

In the absence of guidance specifying a longer wait period for COVID-19, the wait time associated with 99% clearance is an appropriate target for healthcare and other spaces where an infectious occupant is reasonably anticipated to be present. Regardless of whether the 99% or 99.9% column on Table B.1 is used, the value in the table is usually an under-estimation of the actual dilution clearance time as noted in the table’s footnotes which include the following statement: “The times given assume perfect mixing of the air within the space (i.e., mixing factor = 1). However, perfect mixing usually does not occur. Removal times will be longer in rooms or areas with imperfect mixing or air stagnation.” Appropriate use of Table B.1 to establish clearance times from any space requires multiplying the time in the table by a mixing factor (k) that ranges between 1 and 10. This factor represents how well the ventilation system mixes and dilutes the concentration of airborne particles within the room.

As a rule of thumb, rooms with higher airflow rates (6 ACH and higher) and good placement of supply and exhaust grilles (hospital airborne infection isolation rooms) are considered to have “good” mixing and thus a mixing factor of k = 3 is often used for these spaces. In that case, the time identified from Table B.1 should be multiplied by 3 to determine the actual clearance time prior to re-entry. Nonventilated or poorly ventilated spaces have typical values of k ranging from 8 to 10. Increased ACH generally leads to reductions in k, although k can also be reduced by the use of a fan in the space, which does not have an impact on ACH. Ultimately, wait times can be reduced by increasing ACH, reducing k, or a combination of both.

Example 1 . Given: A room measuring 12 feet x 10 feet with a ceiling height of 10 feet is served with a 100% outdoor air ventilation system that delivers 65 cubic feet per minute (cfm) of supply air (Q s = 65 cfm) and exhausts 80 cfm of air from the room (Q e = 80 cfm). The room has average air mixing, so assign k = 5.

Question: How much time is required to reduce the airborne concentration by 99 percent?

Solution: Since Q e is larger than Q s by 15 cfm, the heating, ventilation, and air conditioning (HVAC) system is pulling 15 cfm of air into the room from adjacent areas (i.e., the room is under negative pressure). For this example, the 15 cfm of transfer air is assumed to be free of infectious airborne particles. The clean volumetric air flow rate (Q) is the larger value between Q s and Q e , so Q = 80 cfm. Calculate the air changes per hour:

ACH = [Q x 60] / (room volume) = (80 cfm x 60) / (12’ x 10’ x 10’) = 4800/1200 = 4.0 ACH

Using Table B.1 the perfect mixing wait time based on 4 ACH and a 99% reduction of airborne particles is 69 minutes.

Using the mixing factor of 5, the estimated wait time for 99% reduction of airborne contaminants in the room is 5 x 69 = 345 minutes or 5 hours and 45 minutes.

Note: Determining the true value of the mixing factor is difficult and requires special equipment to measure air flows and conduct tracer gas decay testing. Thus, conservative estimates of k are often used (as described above). Also, the addition of an air cleaning device (e.g., an in-room HEPA filtration unit) within the same room will reduce the wait time. The flow rate from the air cleaning device can be added to Q determined above, which will increase the overall ACH in the room. The air movement created by the air cleaning device can also decrease the value of k. Together, the increased ACH and decreased k can help substantially reduce wait times. See Example 2 at the bottom of FAQ #5 for more information, including an example of the calculations.

Yes, filters with higher collection efficiencies can provide significant reductions in viral particle concentrations.

Filters for use in heating, ventilation, and air conditioning (HVAC) systems are generally tested under procedures outlined in ANSI/ASHRAE Standard 52.2-2017-Method of Testing General Ventilation Air-Cleaning Devices for Removal Efficiency by Particle Size. This standard was developed by ASHRAE, a global society focused on building systems, indoor air quality, and sustainability in the built environment. Based on the filtration efficiency determined by the testing procedures, filters are assigned a Minimum Efficiency Reporting Value (MERV) . The MERV provides a measure of the “filter efficiency” over the range of particle sizes prescribed in the test procedure. MERV values range from 1 to 16 and higher MERV values correspond to more efficient filters.

Research shows that the particle size of SARS-CoV-2 is around 0.1 micrometer (µm). However, the virus generally does not travel through the air by itself. These viral particles are human generated, so the virus is trapped in respiratory droplets and droplet nuclei (dried respiratory droplets) that are larger than an individual virus. Most of the respiratory droplets and particles exhaled during talking, singing, breathing, and coughing are less than 5 µm in size. CDC recommends using MERV 13 filters or filters with the highest efficiency possible, without having detrimental effects on overall HVAC system performance. ASHRAE has similar guidance, which is to “use combinations of filters and air cleaners that achieve MERV 13 or better levels of performance for air recirculated by HVAC systems.” The simplest way to meet this guidance is to use a MERV 13 filter in your appropriately-designed HVAC system, if the system is able to operate properly with it installed. Alternatively, other effective air cleaning technologies can also be used to help meet this performance target. A MERV 13 filter is at least 50% efficient at capturing particles in the 0.3 µm to 1.0 µm size range and 85% efficient at capturing particles in the 1 µm to 3 µm size range. Collectively these particles are capable of remaining airborne for hours and are most associated with deep lung penetration. A MERV 14 filter is at least 75% and 90% efficient, respectively, at capturing those same particles. Efficiencies for MERV 15 and MERV 16 filters are even higher. Thus, the recommended filters are significantly more efficient at capturing particles of concern than a commonly-used MERV 8 filter, which is only around 20% efficient in the 1 µm to 3 µm size range and is not rated for capture efficiency of the smaller 0.3 µm to 1.0 µm particles.

Increasing filtration efficiency can increase the pressure drop (resistance to air flow) across the filters. This can lead to increased fan energy, reduced airflow rates, and/or issues controlling indoor temperature and relative humidity levels. Scientific developments in filter design and manufacturing have reduced the amount of the increased pressure drop and its resulting impact on HVAC operations, but not all filters have adopted the newer technology. Prior to a filtration upgrade, the specific filters under consideration should be investigated for their pressure drop ratings at the flow rate(s) of intended use and the potential impacts of that pressure drop evaluated against the capabilities of the existing HVAC system.

High-efficiency particulate air (HEPA) filters are even more efficient at filtering human-generated infectious particles than MERV 16 filters. However, outside of a few unique applications, HEPA filters are rarely used in central HVAC systems. [See FAQ #5 on HEPA filters and in-room HEPA air cleaners to learn more about them and their application in protective air cleaning].

Directional airflow is a protective ventilation concept where air movement flows in a clean-to-less-clean direction.

This ventilation concept is applied to areas where the “clean” environment requires a higher level of protection and/or where the “less-clean” environment has a higher risk of containing airborne contaminants (activities or occupancy by individuals with a higher risk of being infectious). Examples of “clean” spaces might include healthcare facility triage stations or rooms/corridors adjacent to higher risk activities. Examples of “less-clean” spaces might include spaces that contain known/suspect infectious persons or spaces where a known activity has increased likelihood of generating infectious airborne particles.

The creation of directional airflow can be accomplished within a particular space or between two adjacent spaces. This can be done passively, through intentional placement of supply and exhaust heating, ventilation, and air conditioning (HVAC) grilles, or by the intentional creation of pressure differentials between adjacent spaces through specification of offset exhaust and supply air flow rates. Creation of the directional airflow can also be done actively, through the use of fans exhausting through open windows, strategic placement of ductwork attached to in-room HEPA filtration units, or dedicated exhaust systems (installed or portable) that generate a desired airflow by exhausting air out of windows, doorways, or through temporary ducts. In specific settings, specialized local control ventilation interventions that establish the desired airflow directions can also be used (see the NIOSH Ventilated Headboard ).

Directional airflows must be evaluated carefully. Testing of the directional airflow effectiveness can be accomplished using visual tracer techniques that use “smoke tubes” or handheld “fog generators.” Other tools, such electronic monitors or visual aids to monitor pressure differences can be used when directional airflow is established between two adjacent spaces. To reduce the potential for directing airflow from infectious towards non-infectious space occupants, it is important that the “clean” and “less-clean” space determinations be established using infection control risk assessment considerations.

By definition, a High Efficiency Particulate Air (HEPA) filter is at least 99.97% efficient at capturing particles 0.3 µm in size. This 0.3 µm particle approximates the most penetrating particle size (MPPS) through the filter. HEPA filters are even more efficient at capturing particles larger  and  smaller than the MPPS. Thus, HEPA filters are no less than 99.97% efficient at capturing human-generated viral particles associated with COVID-19.

The excellent capture efficiency of HEPA filters comes at a cost, namely the significant pressure drop (and energy) required to move air through the HEPA filter. For this reason, most traditional HVAC systems are not able to use HEPA filters and are limited to the use of less-efficient filters. To account for the increased pressure requirements, HEPA filtration units often combine a HEPA filter with a dedicated fan system.

In-room HEPA air cleaners that combine a HEPA filter with a powered fan system are a preferred option for auxiliary air cleaning, especially in higher risk settings such as health clinics, vaccination, and medical testing locations, workout rooms, or public waiting areas. Other settings that could benefit from in-room HEPA filtration can be identified using typical risk assessment parameters, such as community incidence rates, facemask compliance expectations, and room occupant density. While these systems do not bring in outdoor dilution air, they are effective at cleaning air within spaces to reduce the concentration of airborne particulates, including SARS-CoV-2 viral particles. Thus, they give equivalent air exchanges without the need for conditioning outdoor air.

In choosing an in-room HEPA air cleaner, select a system that is appropriately sized for the area in which it will be installed. This determination is made based on the air flow through the unit, which is typically reported in cubic feet per minute (cfm). Many portable HEPA filtration units are assigned a Clean Air Delivery Rate (CADR) (See EPA’s Guide To Air Cleaners In The Home ), which is noted on a label in the operator’s manual, on the shipping box, and/or on the filtration unit itself. The CADR is an established standard defined by the Association of Home Appliance Manufacturers (AHAM). Participating portable air cleaner manufacturers have their products certified by an independent laboratory, so the end user can be assured it performs according to the manufacturer’s claims. The CADR is generally reported in cfm for products sold in the United States. The paragraphs below describe how to select an appropriate air cleaner based on the size of the room in which it will be used. The procedure below should be followed whenever possible. If an air cleaner with the appropriate CADR number or higher is not available, select a unit with a lower CADR rating. The unit will still provide incrementally more air cleaning than having no air cleaner at all.

In a given room, the larger the CADR, the faster it will clean the room air. Three CADR numbers are given on the AHAM label, one each for smoke, dust, and pollen. The smoke particles are the smallest, so that CADR number applies best to viral particles related to COVID-19 and other viral respiratory diseases. The label also shows the largest room size (in square feet [ft 2 ]) that the unit is appropriate for, assuming a standard ceiling height of up to 8 feet. If the ceiling height is taller, multiply the room size (ft 2 ) by the ratio of the actual ceiling height (ft) divided by 8. For example, a 300 ft 2 room with an 11-foot ceiling will require a portable air cleaner labeled for a room size of at least 415 ft 2 (300 × [11/8] = 415).

The CADR program is designed to rate the performance of smaller room air cleaners typical for use in homes and offices. For larger air cleaners, and for smaller air cleaners whose manufacturers choose not to participate in the AHAM CADR program, select a HEPA unit based on the suggested room size (ft 2 ) or the reported air flow rate (cfm) provided by the manufacturer. Consumers might take into consideration that these values often reflect ideal conditions which overestimate actual performance.

For air cleaners that provide a suggested room size, the adjustment for rooms taller than 8 feet is the same as presented above. For units that only provide an air flow rate, follow the “ 2/3 rule ” to approximate a suggested room size. To apply this rule for a room up to 8 feet tall, choose an air cleaner with an air flow rate value (cfm) that is at least 2/3 of the floor area (ft 2 ). For example, a standard 300 ft 2 room requires an air cleaner that provides at least 200 cfm of air flow (300 × [2/3] = 200). If the ceiling height is taller, do the same calculation and then multiply the result by the ratio of the actual ceiling height (ft) divided by 8. For example, the 300 ft 2 room described above, but with an 11-foot ceiling, requires an air cleaner that can provide at least 275 cfm of air flow (200 × [11/8] = 275).

While smaller HEPA fan systems tend to be stand-alone units, many larger units allow flexible ductwork to be attached to the air inlet and/or outlet (note that larger ducted units don’t fall under the “room air cleaner” description and may not have a CADR rating). Using ductwork and placing the HEPA system strategically in the space can help provide desired clean-to-less-clean airflow patterns where needed. Ducted HEPA systems can also be used to establish direct source capture interventions for patient treatment and /or testing scenarios (See CDC/NIOSH discussion on Ventilated Headboard ). Depending on the size of the HEPA fan/filter units and how the facility in which they are being used is configured, multiple small in-room HEPA units deployed to high-risk areas may be more useful than one large HEPA unit serving a combined space.

Example 2. Given: The room described in Example 1 at the bottom of FAQ #2 is now augmented with a portable HEPA air cleaning device with a smoke CADR of 120 cfm (Q hepa = 120 cfm). The added air movement within the room improves overall mixing, so assign k = 3.

Question: How much time is saved to achieve the same 99% reduction in airborne contaminants by adding the portable HEPA device to the room?

Solution: The addition of the HEPA filter device provides additional clean air to the room. Here, the clean volumetric air flow rate (Q) is: Q = Q e + Q hepa = 80 cfm + 120 cfm = 200 cfm.

ACH = [Q x 60] / (room volume) = (200 cfm x 60) / (12’ x 10’ x 10’) = 12,000/1,200 = 10 ACH.

Using Table B.1 , the perfect mixing wait time based on 10 ACH and a 99% reduction of airborne particles is 28 minutes.

Using the mixing factor of 3, the estimated wait time for 99% reduction of airborne contaminants in the room is 3 x 28 = 84 minutes. Thus, the increased ACH and lower k value associated with the portable HEPA filtration unit reduced the wait time from the original 5 hours and 45 minutes to only 1 hour and 24 minutes, saving a total of 4 hours and 21 minutes before the room could be safely reoccupied.

Adding the portable HEPA unit increased the equivalent ventilation rate and improved room air mixing. This resulted in over a 75% reduction in time for the room to be cleared of potentially-infectious airborne particles.

Yes, when an appropriate dose of UVGI is applied.

Ultraviolet germicidal irradiation (UVGI), otherwise known as germicidal ultraviolet (GUV), is an air and surface treatment tool used in many different settings, such as residential, commercial, educational, and healthcare settings. The technology uses ultraviolet (UV) energy to inactivate (kill) microorganisms, including viruses, when designed and installed correctly.

UVGI can inactivate viruses in the air and on surfaces.* The design and sizing of effective UVGI treatment systems requires specific knowledge and experience. Seek consultation with a reputable UVGI manufacturer or an experienced UVGI system designer prior to installing UVGI systems. These professionals can assist by properly designing, installing, and commissioning the system for your specific setting.

*Note: CDC’s recommendation for primary surface disinfection in occupied environments is to follow the CDC/EPA guidance for surface disinfection.

UVGI devices can take many shapes and sizes. They can also be mounted in various places.

Depending on the manufacturers’ claims, these devices may be regulated as pesticide devices by the EPA and require efficacy data. In addition, the site where the product is manufactured may also require registration. See the EPA’s Pesticide Devices: A Guide for Consumers for additional information.

Upper-room UVGI Upper-room (or upper-air) UVGI uses specially designed UVGI fixtures mounted on walls or ceilings to create a treatment zone of ultraviolet (UV) energy that is focused up and away from people. These fixtures treat air as it circulates from mechanical ventilation, ceiling fans, or natural air movement. The advantage of upper-room UVGI is that it treats the air closer to and above people who are in the room. Since the 1980s, UVGI systems have been widely used for control of tuberculosis (TB). The CDC guidance Environmental Control for Tuberculosis: Basic Upper-Room Ultraviolet Germicidal Irradiation Guidelines for Healthcare Settings provides information on appropriate UVGI system design, related safe operation, and maintenance. Based on data from other human coronaviruses, a UVGI system designed to protect against the spread of TB should be effective at inactivating SARS-CoV-2 and therefore prevent spread. While small spaces may require a single UVGI fixture, most UVGI systems usually require multiple UV fixtures to be effective. For example, a rectangular-shaped waiting room with 10–30 occupants will require 2–3 upper-air UVGI fixtures. As part of system installation, care must be taken to control the amount of UV energy directed or reflected into the lower occupied space. Reputable UVGI manufacturers or experienced UVGI system designers will take the necessary measurements and make any required adjustments to prevent harmful UV exposures to people in the space.

Potential Application: Can be used as an additional layer of protection to treat the air (kill germs) in indoor spaces; most useful in spaces that host large gatherings or where the risk of disease transmission is high.

In-duct UVGI In-duct UVGI systems are installed within a heating, ventilation, and air conditioning (HVAC) system. These systems are designed to serve one of two purposes:

1) Coil treatment UVGI keeps HVAC coils, drain pans, and wetted surfaces free of microbial growth. These devices produce relatively low levels of UV energy. This energy is continually delivered 24 hours a day, which is why they are effective. Coil treatment UVGI devices are not designed for treating the air and should not be installed for this purpose.

Potential Application: Can be used to reduce HVAC maintenance and improve operational efficiency within large, commercial HVAC systems or residential HVAC systems; not recommended for inactivating airborne pathogens.

2) Air treatment UVGI systems can be effective at applying intense UV energy to inactivate airborne pathogens as they flow within the HVAC duct. HVAC air treatment UVGI systems generally require more powerful UV lamps or a greater number of lamps, or both, to provide the necessary UVGI required to inactivate pathogens in a short period of time. Air treatment systems are often placed immediately downstream of the HVAC coils. This location keeps the coil, drain pan, and wetted surfaces free of microbial growth and also treats the moving air.

Potential Application: Can be used inside any HVAC system to reduce the concentration of infectious airborne pathogens.

Whole-room UVGI Whole-room UVGI (commonly referred to as Far-UV) uses specially designed UVGI fixtures mounted on walls or ceilings to create a treatment zone of ultraviolet (UV) energy that extends throughout an occupied space. While standard UVGI fixtures emit UV energy at a wavelength around 254 nanometers (nm), far-UV devices use different lamps to emit UV energy at a wavelength around 222 nm. Aside from the wavelength, a major difference between the two technologies is that standard UVGI systems are generally designed to avoid exposing people to the UV energy, while many far-UV devices are marketed as safe for exposing people and their direct environment to UV energy. Recent research has indicated 222 nm energy is much safer for humans than once thought. In fact, the American Conference of Governmental Industrial Hygienists (ACGIH) recently increased their Threshold Limit Values (TLVs) 7-fold for eyes and over 20-fold for skin exposed to 222 nm energy. This increase was in response to data showing 222 nm energy does not penetrate the tear layer of the eye or the layer of dead skin (stratum corneum) that protect living skin beneath. Research studies also indicate that far-UV wavelengths can effectively inactivate microorganisms, including human coronaviruses, when appropriate UV doses are applied under experimental conditions. However, there are still some questions about how effective 222 nm energy can be in real occupied spaces against human-generated pathogens when UV exposures are controlled to safe limits.

Far-UV is a promising technology that may well prove to be effective at treating air and surfaces, without some of the safety precautions required for standard UVGI. Due to the potential promise this technology represents, there are substantial private and public research activities underway to further validate claims of safety and efficacy. In the near term, whole-room UVGI is best viewed as new and emerging technology. Consumers considering an emerging technology such as Far-UV should read FAQ #8 on emerging technologies below.

Potential Application : Air and surface treatment in occupied indoor environments.

CDC recommends using technologies that are known to work and will not cause harm. Be cautious when considering an emerging new technology. Do your homework, to include requesting proof of performance and safety under real-world, as-used conditions.

CDC does not provide recommendations for, or against, any manufacturer or product. There are numerous technologies being heavily marketed to provide air treatment during the ongoing COVID-19 pandemic. Common among these are ionization, dry hydrogen peroxide, and chemical fogging. Some products on the market include combinations of these technologies. These products generate ions, reactive oxidative species (ROS, which are marketed using many names), or chemicals into the air as part of the air treatment process. People in spaces treated by these products are also exposed to these ions, ROS, or chemicals. Some research has found these exposures may be harmful under certain conditions, including high concentrations or vulnerable populations.

While variations of these technologies have been around for decades, relative to other air cleaning or treatment methods, they have a less-documented track record when it comes to treating large and fast volumes of moving air within heating, ventilation, and air conditioning (HVAC) systems or even inside individual rooms. This does not necessarily imply the technologies do not work as advertised. However, in the absence of an established body of peer-reviewed evidence showing proven efficacy and safety under as-used conditions, the technologies are still considered by many to be “emerging.”

As with all emerging technologies, consumers are encouraged to exercise caution and to do their homework. A manufacturer’s reference to regulation and/or product registration, with national or local authorities, does not always imply specific product efficacy or safety. Consumers should research the technology, attempting to match any specific claims against the intended use of the product. Consumers should request testing data that quantitively demonstrates a clear protective benefit and occupant safety under conditions consistent with the intended use. When considering air treatment technologies that potentially or intentionally expose building occupants, the safety data should be applicable to all occupants, including those with health conditions that could be aggravated by the air treatment. In transient spaces, where average exposures to the public may be temporary, it is important to also consider occupational exposures for workers that must spend prolonged periods in the space.

Preferably, the documented performance data under as-used conditions should be available from multiple sources, some of which should be independent, third-party sources. Unsubstantiated claims of performance or limited case studies with only one device in one room and no reference controls should be questioned. At a minimum, when considering the acquisition and use of products with technology that may generate ozone (a gas with potentially harmful health effects), verify that the equipment meets UL 2998 standard certification (Environmental Claim Validation Procedure (ECVP) for Zero Ozone Emissions from Air Cleaners) which is intended to validate that no ozone is produced.

Yes, carbon dioxide (CO 2 ) monitoring can provide information on ventilation in a given space, which can be used to enhance protection against COVID-19 transmission. Strategies incorporating CO 2 monitors range in cost and complexity. However, greater cost and complexity does not always mean greater protection.

Limited information exists regarding a direct link associating CO 2 concentration to a risk of COVID-19 transmission. Changes in CO 2 concentrations can indicate a change in room occupancy and be used to adjust the amount of outdoor air delivered. However, CO 2 concentrations cannot predict who has COVID-19 infection and might be spreading the virus, the amount of airborne viral particles produced by infected people, or whether the HVAC system is effective at diluting and removing viral concentrations near their point of generation. Ventilation based on CO 2 measurements cannot recognize the increased risk of transmission when multiple room occupants are infected.

In some well-designed, well-characterized, well-maintained HVAC environments, the use of fixed CO 2 monitors can be informative. When used, these monitors are often incorporated into demand-controlled ventilation (DCV) systems that are designed with a primary intent of maximizing energy efficiency through reductions in outdoor air delivery. However, during times of high community transmission, guidance is often to deactivate DCV systems and exceed minimum ventilation whenever possible, in addition to enhanced filtration, and other intervention-focused considerations.

Traditionally, CO 2 monitoring systems are expensive, require extensive knowledge to accurately install and set up, and require sophisticated control programs to effectively interact with the building heating, ventilation and air conditioning (HVAC) systems in real time. They were not designed to protect building occupants from disease transmission. Fixed-position CO 2 monitors measure CO 2 concentration as an indicator of the number of people in the space. As the CO 2 concentration increases, the HVAC DCV system increases the amount of outdoor air ventilation in the space to dilute CO 2 (and vice versa). The number of CO 2 sensors, the placement of those sensors, and their calibration and maintenance are collectively a large and complex issue that must not be overlooked. For example, the CO 2 concentration measured by a fixed, wall-mounted monitor may not always represent the actual concentrations in the occupied space. If air currents from the room HVAC, or even make-up air from windows, flows directly over this monitor location, the corresponding concentration measurements will be artificially low. If the room has good air mixing, the measured concentration should approximate the true concentration, but rooms are rarely well mixed, particularly in older buildings with aging ventilation systems (or none at all). Also, if an elevated CO 2 concentration results in an air flow increase to one room, that air may be “stolen” from other rooms on the same HVAC system. This may result in elevated CO 2 concentrations in those other spaces which the HVAC system is unable to control.

A more modest, cost-efficient, and accurate use of CO 2 monitoring is the use of portable instruments combined with HVAC systems that do not have modulating setpoints based on CO 2 concentrations. The CO 2 meter can be purchased for under $300 and its measurements can be collected/logged near the breathing zones of occupied areas of each room. It is critical to select calibrated CO 2 meters whose sensors are reliable and accurate to draw meaningful inferences from measured indoor CO 2 concentrations. Under this approach, validate that the HVAC system is operating appropriately and is meeting or exceeding code-minimum outdoor air requirements based on current use and occupancy. Next, measure the resulting CO 2 concentrations in rooms under as-used conditions using a handheld portable CO 2 meter. These observations will be the CO 2 baseline concentrations for each room under the HVAC operating conditions and occupancy levels.

One potential target for the baseline concentrations that is used to represent good ventilation is CO 2 readings below 800 parts per million (ppm). It is important to note, however, that a single concentration value may not be an appropriate target for all space types and occupancies for the purposes of assessing the ventilation rate (see ASHRAE Position Document on Indoor Carbon Dioxide). Once a target concentration is identified, compare your baseline concentrations to the target concentration. If a baseline measurement is above the target, reevaluate the context under which the measurement was obtained and if warranted, investigate the ability to increase outdoor air delivery. If unable to get below your target CO 2 value, increased reliance on enhanced air filtration (including in-room HEPA air cleaners) may be necessary. Once the baseline concentrations are established, take periodic measurements in each space and compare those to the initial baselines. As long as ventilation airflow is unchanged (outdoor air or total air) and occupancy capacity is not increased, future portable CO 2 concentrations that exceed 110% of the baseline concentrations indicate a potential problem that should be investigated.

Generally, no. Temperature and humidity can both influence the transmission of infectious diseases, including COVID-19, but that influence has practical limitations in occupied spaces of buildings.

Research on the impact of temperature has shown that SARS-CoV-2, the virus that causes COVID-19, is sensitive to elevated temperatures, with over 99.99% inactivation in only a few minutes at 70°C (158°F). However, this temperature is far outside the limits of human comfort and could damage some building materials. While temperatures lower than 70°C (158°F) are also effective, the required exposure time for inactivation increases as the temperature decreases. So, elevated temperatures offer the potential for decontamination of SARS-CoV-2 virus in the air or on surfaces, but the use of increased temperature solely for decontamination is not generally recommended and is not realistic for occupied spaces.

Based on current evidence, it is not clear whether, in practice, increasing humidity could significantly reduce transmission of COVID-19 beyond the reductions that result from using good ventilation and filtration. Several scientific research studies have concluded that influenza and SARS-CoV-2 viruses do not survive as well in environments with higher humidity compared with lower humidity. However, the reasons for this are unclear, and artificial experimental factors like the size of the liquid droplets used in the experiments and the composition of the liquid containing the viruses affect the results. Thus, there is still debate within the scientific community over how much humidity affects virus survival outside of the laboratory. Adding humidity to indoor environments, especially in very cold climates, can also introduce additional challenges to the building environment. CDC and standards-setting organizations like ASHRAE do not make recommendations about controlling indoor humidity to reduce virus survival, although humidity recommendations are made for other reasons, such as prevention of dust mite and mold growth or reduction of static electricity. While not affecting transmission, there are peer-reviewed studies that suggest preventing excessive dryness in the air could help maintain the effectiveness of the human body’s immune system.

Yes, but with caution.

While fans alone cannot make up for a lack of outdoor air, fans can be used to increase the effectiveness of open windows, as described in the CDC list of ventilation mitigation strategies . Fans can also be used indoors to improve room air mixing. Improved room air mixing helps distribute supplied clean air and dilute viral particle concentrations throughout the room, which reduces the likelihood of stagnant air pockets where viral concentrations can accumulate. As with all fan use during the COVID-19 pandemic, take care to minimize the potential to create air patterns that flow directly across one person onto another:

Avoid the use of the high-speed settings
Use ceiling fans at low velocity and potentially in the reverse-flow direction (so that air is pulled up toward the ceiling)
Direct the fan discharge towards an unoccupied corner and wall spaces or up above the occupied zone.

Fans can also enable clean-to-less-clean directional airflow. Such applications should be evaluated closely to avoid unintended consequences and only adopted when supported by a safety risk assessment.

Barriers can help or barriers can hurt. It depends on where and how they are deployed.

Barriers can physically separate spaces that are next to each other. When used for infection control, the barrier is intended to prevent someone on one side of the barrier from exposing a person on the other side of the barrier to infectious fluids, droplets, and particles. Whether a barrier interferes with improved ventilation depends on how it is installed. Protective barriers can sometimes help improve ventilation, but they can sometimes hinder ventilation too. Sometimes they have no effect on ventilation.

Protective barriers can assist with improved ventilation when used to facilitate directional airflows or desired pressure differentials between clean and less-clean spaces. The barrier can be aligned with the intended airflow to help direct it towards a desired location, such as an HVAC return air grille or an in-room HEPA air cleaner inlet. Example scenarios for this type of barrier deployment include those where there is a known source of potentially infectious aerosols, such as a dental operatory or COVID-19 testing station.

Alternatively, the barrier might be placed between two areas to better isolate one side of the barrier from the other. In this configuration, the barrier can also assist the HVAC design scheme in establishing a desired pressure differential between the adjacent spaces. If necessary, small pass-through openings or a retractable panel incorporated into the barrier can allow transfer of physical objects from one side to the other. Examples where this type of barrier application might be applied include a receptionist’s desk or a ticket booth.

When not carefully installed, barriers can sometimes hinder good ventilation. Barriers can unintentionally interrupt the airflow distribution within a space, thus allowing a concentration build-up of human-generated or other aerosols that may remain suspended in the air for minutes to hours. In this case, people could be exposed to higher concentrations of infectious aerosols than they would without the barriers in place. The larger the barrier, the greater the likelihood that this may occur. To reduce this likelihood, ensure that barriers are correctly positioned for the anticipated occupancy and that they are no larger than necessary to prevent direct transfer of respiratory droplets that could “spray” directly from one person onto another.

Any time barriers are deployed, airflow distribution testing with tracer “smoke” or handheld fog generators should be conducted. This testing can assist in evaluating airflow distribution within the occupied spaces. If stagnant air pockets are seen to occur, barrier redesign or reorientation can help to minimize the occurrence. Airflow distribution modifications such as adjusting the positioning of supply air louvers or the discharge of in-room air cleaners can also assist in eliminating the development of stagnant air pockets.

Note: The installation of barriers should not interfere with emergency egress or with the protective function of fire sprinklers. When in doubt, consultation with local code and fire officials is encouraged.

Yes, when built and used correctly, they can be a protective temporary intervention.

Adding filtration and air movement to a space is generally better than doing nothing when it comes to reducing potential risks from viral particles in the air. Well-constructed do-it-yourself (DIY) air cleaners can serve this purpose. When constructed with great attention to detail, DIY air cleaners have been shown to be effective. Their effectiveness and safety have been supported by the U.S. Environmental Protection Agency (EPA) to reduce wildfire smoke indoors. The particle sizes associated with wildfire smoke include the 1 – 3 micrometer (µm) particles associated with human-generated viral particles, like those that cause COVID-19. Thus, DIY air cleaners can help reduce exposure to those airborne viral particles.

DIY air cleaners are appropriate during emergencies, for short-term use, or when obtaining commercially-available air cleaners, for whatever reason, is not possible. However, DIY air cleaners should not be used as a permanent, long-term solution for in-room air cleaning. Commercially-available portable air cleaners with high-efficiency particulate air (HEPA) filters are preferred and should be used whenever possible. These units have an established Clean Air Delivery Rate (CADR), which is an established standard defined by the Association of Home Appliance Manufacturers (AHAM). For more information, see the Environmental Protection Agency (EPA) Guide To Air Cleaners In The Home ). Participating portable air cleaning manufacturers have their products certified by independent laboratories to assure they perform according to the manufacturer’s claims.

DIY air cleaners are generally assembled from box fans and square heating, ventilation and air conditioning (HVAC) filters. Different configurations can be found online that use anywhere from 1 to 5 HVAC filters. A common version, using 4 HVAC filters is often referred to as a Corsi-Rosenthal Box. Regardless of the design, the HVAC filters are sealed to the inlet side of the box fan. Using multiple filters can reduce the resistance to air flow, allowing the fan to move more air when more filters are used in the design. Air cleaning is achieved when the fan pulls contaminated air through the filter and releases the filtered air back into the space through the fan outlet. For these to provide effective air cleaning, they must be assembled properly to eliminate air leaks between individual filters (when multiple filters are used) and where the filters are sealed to the box fan itself. Adequate amounts of duct tape should be used to prevent leaks during assembly. Air leaks reduce the effectiveness of the air cleaner, and this effect can be magnified as the HVAC filter(s) load with dust and the resistance through the filter(s) increases.

In addition to air leaks resulting in filter bypass, the overall performance of DIY air cleaners will depend on the individual box fan and HVAC filters selected. Individual units may perform better or worse than expected. Unless the completed DIY air cleaner is thoroughly tested, a rating akin to the CADR will be unknown. However, the performance of well-assembled DIY units can be approximated by measuring the air exhausted from the fan (using an air flow hood or other similar equipment to measure air flow) and multiplying by the efficiency of the filters at capturing 1 to 3 micrometer (µm) particles. As an example, MERV 13 filters are at least 85% efficient at capturing particles in that size range. A DIY air cleaner capable of moving 300 cubic feet per minute (cfm) of air through MERV 13 filters, would provide 255 cfm (300 cfm × 0.85 = 255 cfm) of ”clean” air. However, keep in mind that is simply an approximation and likely represents the best-case performance.

While similar to commercially available HEPA air cleaners, the introduction of DIY air cleaners in a space can introduce new issues that need to be considered. Electrical cords for the fan need to be secured to prevent causing a tripping hazard. The DIY air cleaners can create enough noise to create difficulties communicating verbally. This often causes the units to be turned off or operated at a lower and less-effective fan setting, which defeats the purpose of having the air cleaner in the first place. As with all air cleaners, the DIY units need to be positioned in the room to prevent strong air flows from one person directly over another.

Previous Updates

As of June 2, 2021

Added a new Frequently Asked Question on protective barriers and ventilation.

As of March 23, 2021

Simplified language in the overall list of tools to improve ventilation.
Added three new Frequently Asked Questions (FAQs) on the usefulness of carbon dioxide monitors to inform ventilation decisions, the usefulness of temperature and relative humidity to control the spread of COVID-19, and the use of fans indoors.
Expanded the FAQ on emerging technologies to include more products available on the market.
Added additional information with simple calculations to the FAQ on portable HEPA air cleaners to help consumers choose appropriate units for their spaces.

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IMAGES

The Pediatric Center of Frederick
Well-Child Checks
Well child visits
Importance of Well Child Visits During COVID-19
Well-Child Care Visits
Department of Social Services

COMMENTS

CDC's Developmental Milestones
Download CDC's free Milestone Tracker App. View. Skills such as taking a first step, smiling for the first time, and waving "bye bye" are called developmental milestones. Children reach milestones in how they play, learn, speak, act, and move. Click on the age of your child to see the milestones: 2 months. 4 months.
Developmental Monitoring and Screening
The American Academy of Pediatrics (AAP) recommends developmental and behavioral screening for all children during regular well-child visits at these ages: 1. 9 months. 18 months. 30 months. In addition, AAP recommends that all children be screened specifically for autism spectrum disorder (ASD) during regular well-child visits at: 18 months.
What Exposure Questions Should Be Included in a Well Child Visit?
describing how to take a screening exposure history for a well child visit. Skip directly to site content Skip directly to search. ... (CDC) lead poisoning prevention guidelines [CDC 1997]. A general pediatrician's practice allows little time for an extensive environmental exposure history. However, initial and subsequent well child visits do ...
PDF The Well-Child Visit
What to expect during your visit A well-child visit is a chance to get regular updates about your child's health and development. Your health care team will take measurements, conduct a head-to-toe examination, update immunizations, and offer you a chance to talk with your health care professional. Your well-child visit includes 4 specific ...
Preventive Health Care Visits in Children
Scheduled visits to the doctor (also called well-child visits) provide parents with information about their child's growth and development. Such visits also give parents an opportunity to ask questions and seek advice, for example, about toilet training.. The American Academy of Pediatrics recommends that after the first year of life children should see their doctor for preventive health care ...
Child wellness visits are more important than ever during the COVID-19
Dr. Lerner says families and caretakers should prioritize well-child or wellness visits, especially when it comes to vaccinations. The Centers for Disease Control and Prevention published data which show in the spring, 2.5 million fewer doses of routine vaccines were ordered, compared to the same period in 2019.
Preventive Health Care Visits in Infants
Preventive health care visits (also called well-child visits) typically take place within a few days after birth or by 2 weeks of age and at 1, 2, 4, 6, and 9 months of age. During these visits, the doctor uses age-specific guidelines to monitor the infant's growth and development and asks the parents questions about various developmental ...
Well child exams and immunizations
Schedule of exams and immunizations. Newborn - 9 months exam and immunization schedule. Years 1 - 4 exam and immunization schedule. Years 5 - 10 exam and immunization schedule. Years 11 - 19+ exam and immunization schedule. Click here for a printable exam and immunization chart that covers birth to age 18.
Integration of Oral Health Into the Well-Child Visit at Federally
Study Title: Integration of Oral Health Into the Well-Child Visit at Federally Qualified Health Centers: Study of 6 Clinics, August 2014-March 2015 CME Questions. You are seeing a 2-year-old girl for a well-child examination. Her parents report no health concerns, and you consider her risk for chronic illness.
Products
This report describes physician office visits for well and problem-focused care among children under age 18 years. This analysis complements the information on children's visits contained in the National Ambulatory Medical Care Survey (NAMCS) 2012 online tables . Keywords: well-child care, ambulatory care, National Ambulatory Medical Care Survey
Well Child Visits: What Parents Need to Know
Well child visits are very important for ALL kids, especially those 24 months and younger, and it is recommended to keep these appointments on schedule. During a well-child visit, your provider will: Perform a physical exam. At the beginning of the visit our wonderful nursing team will obtain your child's height, weight, and vital signs ...
Well-child visit (newborn and infant): Clinical sciences
In the first year of life, each well-child visit starts with a comprehensive history and physical exam, followed by age-specific interventions and recommendations. Your goal at each well-infant visit is to provide age-appropriate screenings and immunizations; assess development; counsel on nutrition and oral health as indicated; and provide ...
Well-Check Schedule for Children
These vaccines, mostly given as shots at a well-child visit, are very safe and can help prevent easily spread diseases that can cause serious health problems. ... [CDC]. COVID-19 vaccines can be ...
AAP Schedule of Well-Child Care Visits
The Bright Futures/American Academy of Pediatrics (AAP) developed a set of comprehensive health guidelines for well-child care, known as the "periodicity schedule." It is a schedule of screenings and assessments recommended at each well-child visit from infancy through adolescence. Schedule of well-child visits. The first week visit (3 to 5 ...
QuickStats: Percentage of Children Aged 18 Years Who Received a Well
Receipt of a well-child checkup increased for all age groups: from 86.7% to 91.9% among those aged 0-4 years, from 74.5% to 86.9% among those aged 5-11 years, and from 68.0% to 81.7% among those aged 12-17 years. For both 2008 and 2018, the percentage of children who received a well-child checkup decreased as age increased.
Redesigning Primary Care Well Child Visits: A Group Model
Background: Providing effective, efficient well child-care can be challenging. Many obstacles exist for delivering well child-care to low-income populations including time, cultural barriers and limited resources. Urban, immigrant populations face unique social circumstances and stand to benefit from a model of care that provides parents with enhanced support and education. Group well child ...
Child's Well Visit, 12 Months: Care Instructions
Brush your child's teeth every day. Use a tiny amount of toothpaste with fluoride. Put sunscreen (SPF 30 or higher) and a hat on your child before going outside. Keeping your baby safe. Don't leave your child alone around water, including pools, hot tubs, and bathtubs. Always use a rear-facing car seat.
Well-Child Visit Adherence
Well-child care, as recommended by the American Academy of Pediatrics' Bright Futures guidelines, 1 provides children with preventive and developmental services, helps ensure timely immunizations, and allows parents to discuss health-related concerns. 2 We know from prior studies 3,4 that as of 2008, well-child visits were trending upward ...
Well-Child Visits for Infants and Young Children
Immunizations are usually administered at the two-, four-, six-, 12-, and 15- to 18-month well-child visits; the four- to six-year well-child visit; and annually during influenza season ...
Vaccines for Your Children
Answer a few quick questions to get a list of vaccines your child may need. Also available in Spanish. Take the Quiz. Vaccine Schedule. Stay on track with your child's vaccines by following the recommended immunization schedules. Follow the Schedules
CDC Archives
CDC Archive Home. Archived web material for CDC.gov is preserved on the CDC Archive Site. Note that the content on this site is for historical purposes only and is no longer being updated. The information here may be outdated and links may no longer function. Search the Archives
Well-Child Visits: Appointments, Immunizations, and More
flu. 4 years old. DTaP. IPV. MMR. varicella. flu. After age 4, a well-child visit should take place every year and should include a physical exam and a growth, developmental, behavioral, and ...
Parent Information
Parent Information. Tips for Parents Information About Infants & Toddlers (Ages 0-3) Information About Young Children (Ages 4-11) Information About Teens (Ages 12-19) Site Index. Tips for Parents. Provides an overview of CDC's Parenting Information Portal. Learn More.
Mexico Travel Advisory
Reissued after periodic review with general security updates, and the removal of obsolete COVID-19 page links. Country Summary: Violent crime - such as homicide, kidnapping, carjacking, and robbery - is widespread and common in Mexico.The U.S. government has limited ability to provide emergency services to U.S. citizens in many areas of Mexico, as travel by U.S. government employees to ...
Well-Child Visit: What's Included and When to Go
Take blood pressure. Measure oxygen levels. Listen to your child's lungs. Look at your child's eyes, ears, and throat. Press on your child's tummy to feel organs. Move your child's hips ...
Cleaning, Disinfecting, and Ventilation
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COVID-19 Vaccine: What You Need to Know
Speak with your pediatrician if you have questions about having your child vaccinated. If I recently had COVID-19, do I need a 2023-2024 vaccine? If you recently had COVID-19, the CDC recommends waiting about three months before getting this updated vaccine. If you encounter the virus again, having the updated vaccine will:
How to Protect Yourself and Others
CDC recommends that all people use core prevention strategies to protect themselves and others from COVID-19: Stay up to date with COVID-19 vaccines.. Although vaccinated people sometimes get infected with the virus that causes COVID-19, staying up to date on COVID-19 vaccines significantly lowers the risk of getting very sick, being hospitalized, or dying from COVID-19.
Ventilation in Buildings
Although there are some highly contagious airborne diseases (like measles) where CDC provides specific guidance for 99.9% clearance wait times, the general recommendation in CDC's Guidelines for Environmental Infection Control in Health-Care Facilities is to wait to allow for a 99% reduction of any generated airborne particles before re ...

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