Indoor Air Quality in Child Care: Lessons from COVID-19

Before the COVID-19 pandemic, indoor air quality in child care settings received little attention from policymakers, operators, or parents. Infection control focused on handwashing, surface cleaning, and keeping visibly sick children home. These practices remain important for preventing gastrointestinal infections and some respiratory illnesses, but the pandemic revealed their limitations. Many respiratory pathogens, including SARS-CoV-2, influenza, respiratory syncytial virus, and measles, spread efficiently through airborne transmission, meaning infectious particles can remain suspended in indoor air for extended periods and infect people well beyond close contact distance.

This recognition fundamentally changed how public health experts think about preventing respiratory disease transmission in congregate settings. Good ventilation and air filtration reduce the concentration of infectious particles in indoor air, lowering transmission risk regardless of surface cleaning or handwashing compliance. Poor ventilation, conversely, allows pathogens to accumulate in enclosed spaces, increasing infection rates even when other protocols are followed rigorously.

The implications for child care are profound. Children spend long hours indoors in close proximity, breathing the same air. They cannot wear masks reliably; they touch their faces frequently; their immune systems are still developing. When ventilation is inadequate, respiratory viruses spread rapidly through classrooms, leading to clusters of sick children, staff absences, and sometimes program closures. As outlined in our comprehensive framework for health readiness in child care expansion, the built environment is one of three essential domains that determines whether programs can maintain safe, stable operations.

As New York invests more than $2.2 billion in expanding child care capacity, indoor air quality must be treated as core infrastructure rather than a luxury. This post examines the evidence base for ventilation improvements, practical strategies for different facility types, and policy mechanisms to embed air quality standards into child care expansion efforts.

How Indoor Air Quality Affects Disease Transmission

When an infected person breathes, speaks, coughs, or sneezes, they release respiratory particles of varying sizes. Large droplets fall quickly to surfaces, where they can be addressed through cleaning. But smaller aerosol particles remain airborne, carried by air currents throughout a room and even between rooms if ventilation systems recirculate air without adequate filtration. These aerosols can contain live viruses that remain infectious for minutes to hours depending on the pathogen and environmental conditions.

In a poorly ventilated room, infectious aerosols accumulate over time. Each infected person adds to the viral load in the air; uninfected people inhale this contaminated air and may become infected even if they maintain physical distance from the source. In a well-ventilated room, outdoor air continuously dilutes the concentration of aerosols, and filtration removes particles from recirculated air. The result is lower viral exposure and reduced transmission risk.

This mechanism has been demonstrated repeatedly through outbreak investigations. During the COVID-19 pandemic, numerous superspreading events occurred in poorly ventilated indoor spaces including restaurants, offices, churches, and care facilities, where a single infected individual transmitted the virus to many others present. Conversely, outdoor gatherings, even with large crowds, rarely produced comparable transmission because outdoor air provides effectively infinite ventilation.

The same principles apply to child care settings. A child with influenza in a well-ventilated classroom may infect one or two close contacts; in a poorly ventilated classroom, the same child can infect half the room over the course of a day. Improving ventilation does not eliminate transmission risk entirely, but it substantially reduces it, making the difference between manageable illness rates and disruptive outbreaks.

For a detailed explanation of how indoor air quality improvements reduce disease transmission risk, including specific mechanisms and research findings, see this in-depth FAQ on the science of air quality and infection control.

Current State of Ventilation in Child Care Facilities

Ventilation quality in child care settings varies dramatically. Newer facilities built to modern codes often have mechanical HVAC systems that bring in outdoor air, filter recirculated air, and maintain reasonable air exchange rates. Older facilities, particularly those operating in converted residential buildings or repurposed commercial spaces, may rely primarily on operable windows for ventilation or have aging HVAC systems that no longer function effectively.

Home-based child care programs, which serve a significant portion of infants and toddlers in New York, typically have residential ventilation systems not designed for congregate care. These systems may provide adequate air quality for a family household but insufficient air exchange when ten children and two adults occupy a single room for hours.

Many operators have limited understanding of their ventilation systems. They may not know the air exchange rate in their classrooms, whether their HVAC filters are adequate for pathogen removal, or how often filters should be changed. Inspection systems have historically focused on visible hazards such as structural safety, fire exits, and sanitation, with ventilation receiving little attention unless systems were obviously broken.

The COVID-19 pandemic prompted some improvements. New York City public schools upgraded HVAC systems to include MERV-13 filters, installed portable air purifiers in classrooms, and modified windows to allow natural ventilation. These investments improved indoor air quality substantially, contributing to lower COVID-19 transmission rates in schools compared to many other congregate settings. However, most child care facilities did not receive similar support, leaving a patchwork of conditions ranging from adequate to poor.

Evidence-Based Ventilation Standards

Setting appropriate ventilation standards for child care requires balancing public health benefit, technical feasibility, and cost. The American Society of Heating, Refrigerating and Air-Conditioning Engineers publishes standards for ventilation in various building types, recommending minimum outdoor air exchange rates based on occupancy and activity level. For educational facilities, ASHRAE recommends outdoor air delivery rates of at least 10 liters per second per person, equivalent to about six air changes per hour in a typical classroom.

During the COVID-19 pandemic, experts recommended enhanced ventilation targets including 12 or more air changes per hour where feasible, particularly in settings serving populations at higher risk such as young children who cannot be vaccinated or wear masks effectively. These targets can be met through combinations of mechanical ventilation, natural ventilation through windows, and portable air purifiers.

Air filtration quality is equally important. Standard HVAC filters are rated using the Minimum Efficiency Reporting Value system, where higher MERV ratings indicate better filtration of small particles. Basic residential filters typically have MERV ratings of 4 to 8, capturing large particles but allowing smaller aerosols to pass through. MERV-13 filters capture at least 85 percent of particles in the size range most relevant for airborne virus transmission, providing substantial public health benefit when used in HVAC systems.

Portable air purifiers with HEPA filters offer an alternative or supplement to upgraded HVAC systems, particularly in spaces where mechanical ventilation cannot be easily improved. HEPA filters capture at least 99.97 percent of particles, providing excellent air cleaning when units are appropriately sized for room volume and positioned to maximize air circulation.

For comprehensive guidance on clean indoor air and health benefits, including practical implementation strategies, see this detailed article on what you need to know about indoor air quality improvements.

Practical Strategies for Different Facility Types

New Construction and Major Renovation

New child care facilities and those undergoing major renovation offer the best opportunity to install high-quality ventilation systems from the outset. Capital grant criteria should require mechanical ventilation systems meeting ASHRAE standards, HVAC equipment sized appropriately for occupancy, MERV-13 or better filtration, and controls that allow monitoring of system performance. These requirements should be non-negotiable conditions of public funding for facility development.

Design should also consider natural ventilation through operable windows as backup or supplement to mechanical systems, recognizing that HVAC systems require maintenance and sometimes fail. Windows that open safely, with screens and guards to prevent falls, provide resilience and connection to outdoor environments that benefit child development beyond air quality alone.

Existing Facilities with Functional HVAC Systems

Many existing child care facilities have HVAC systems that function but use inadequate filters. Upgrading to MERV-13 filters is often straightforward and relatively inexpensive, though systems should be evaluated to ensure they can handle the increased airflow resistance of higher-efficiency filters without reducing air exchange rates or damaging equipment. Professional HVAC technicians can assess system capacity and make minor modifications if needed to accommodate better filters.

Filter maintenance is critical. Even high-quality filters lose effectiveness as they become clogged with captured particles. Facilities should implement schedules for regular filter inspection and replacement, typically every three to six months depending on environmental conditions and system usage. This ongoing cost should be factored into operating budgets and supported through adequate subsidy reimbursement rates.

Facilities with Inadequate or Absent HVAC Systems

Older buildings and home-based programs often lack mechanical ventilation adequate for congregate care. Portable air purifiers with HEPA filters offer a practical solution. Multiple units appropriately sized and positioned can provide air cleaning equivalent to or better than upgraded HVAC filtration, though they do not bring in outdoor air and thus should be combined with natural ventilation through windows when weather permits.

Guidance is needed on selecting, sizing, and positioning portable units. The key metric is Clean Air Delivery Rate, measured in cubic feet per minute, which indicates how quickly a unit can filter air in a given space. Units should be sized to provide at least five air changes per hour based on room volume, positioned to maximize air circulation without creating drafts that disturb children, and operated continuously during occupied hours.

Carbon dioxide monitors provide a simple, low-cost tool for assessing ventilation adequacy. Carbon dioxide is exhaled by occupants and accumulates in poorly ventilated spaces. Levels above 1000 parts per million indicate insufficient outdoor air exchange. Portable monitors cost less than $200 and can help providers identify ventilation problems and assess whether interventions such as opening windows or adding air purifiers are effective.

Implementation Challenges and Solutions

Cost and Funding

Ventilation improvements require upfront capital investment and ongoing operating costs. HVAC system upgrades can range from a few thousand dollars for filter upgrades to tens of thousands for complete system replacement. Portable air purifiers cost several hundred dollars per unit, and facilities may need multiple units. These are significant expenses for programs operating on thin margins.

New York should dedicate a minimum of 15 percent of any child care capital expansion grant to health and safety infrastructure, with ventilation explicitly included in eligible uses. This requirement ensures that expansion does not occur in facilities with poor air quality. For existing facilities not undergoing renovation, targeted grants for ventilation improvements should be available on a priority basis to programs serving high-need communities or operating in older buildings.

Operating costs including electricity for air purifiers and replacement filters should be recognized in subsidy reimbursement rate calculations. State and local governments set reimbursement rates based on estimated costs of providing care; these estimates should include realistic allowances for maintaining healthy indoor environments.

Technical Capacity and Expertise

Many child care operators lack technical knowledge about ventilation systems. They may not know how to assess current ventilation quality, select appropriate improvements, or maintain equipment properly. State agencies should provide technical assistance including guidance documents with clear specifications for different facility types, lists of qualified vendors and contractors, and training for program administrators on basic HVAC concepts and maintenance.

Child Health Care Consultants, if established as recommended in earlier posts in this series, could include ventilation assessment in their scope of work, helping programs identify problems and connect with resources to address them. Local health departments could also play a role, particularly in investigating illness outbreaks where poor ventilation may have contributed.

Balancing Ventilation with Energy Efficiency and Comfort

Increasing outdoor air exchange and running air purifiers continuously increase energy consumption, potentially creating tension with energy efficiency goals and raising utility costs. This is a real concern but should not prevent necessary improvements. The public health benefits of good ventilation far outweigh incremental energy costs, and energy-efficient HVAC equipment can minimize the trade-off.

Thermal comfort is another consideration. Bringing in outdoor air when temperatures are very hot or very cold can make indoor spaces uncomfortable unless HVAC systems can heat or cool the incoming air adequately. Natural ventilation through windows may not be practical during temperature extremes. These constraints mean that ventilation strategies must be tailored to local climate and building characteristics, with mechanical systems, portable purifiers, and natural ventilation used in combination based on seasonal conditions.

Incorporating Air Quality Standards into Licensing and Inspection

Ventilation requirements should be incorporated into licensing standards for child care facilities. At minimum, these standards should require functional mechanical ventilation or operable windows, use of MERV-13 or better filters in HVAC systems, deployment of portable air purifiers in rooms below defined ventilation thresholds, and use of carbon dioxide monitors to verify ventilation adequacy. Standards should apply to all licensed providers and be phased in with technical assistance and capital support for programs that need to upgrade.

Inspection protocols should include verification of ventilation quality. Inspectors should check that HVAC systems are operating, filters are clean and appropriately rated, air purifiers are present and functioning where required, and carbon dioxide levels are reasonable during occupied hours. These checks need not be complex; simple visual inspection of equipment and spot measurements with portable monitors can identify obvious deficiencies that warrant follow-up.

As with other health and safety standards, enforcement should be supportive rather than purely punitive. Programs that are found to have ventilation deficiencies should be given clear guidance, reasonable timelines for correction, and assistance in accessing funding for necessary improvements. The goal is to raise baseline air quality across the system, not to close programs for fixable problems.

Relevance Beyond COVID-19: Bird Flu and Future Respiratory Threats

While COVID-19 catalyzed attention to indoor air quality, the relevance extends far beyond one pathogen. Influenza, RSV, measles, tuberculosis, and many other respiratory infections spread through airborne transmission. Seasonal influenza causes substantial illness and disruption in child care settings every winter; improved ventilation could reduce transmission and allow programs to remain open and fully staffed during flu season.

Emerging threats such as avian influenza, which has shown concerning patterns of spread to mammals including humans in recent years, underscore the importance of built-in ventilation resilience. If a novel influenza strain with high transmissibility emerges, facilities with good ventilation will be better positioned to continue operations safely. As discussed in this analysis of bird flu preparedness and indoor air quality in schools and nursing homes, investing in ventilation now provides protection against both current and future respiratory pathogens.

Climate change is also creating new air quality challenges. Wildfire smoke events, which have become more frequent and severe, produce fine particulate matter that penetrates indoor spaces and exacerbates respiratory conditions such as asthma. Good filtration protects children during smoke events, allowing programs to remain open when outdoor air quality is hazardous. This dual benefit for infectious disease control and environmental protection strengthens the case for ventilation investments.

Co-Location in Schools as a Ventilation Strategy

One powerful strategy for improving air quality in child care is co-locating programs in underutilized public school buildings. Schools are generally built to more rigorous ventilation standards than standalone child care facilities, and many underwent substantial air quality improvements during the COVID-19 pandemic. New York City schools, for example, now have upgraded HVAC systems with MERV-13 filtration and portable air purifiers in classrooms.

When child care programs operate in school buildings, they inherit these improvements. This raises baseline air quality for young children while simultaneously expanding capacity and reducing facility costs. Co-location is not feasible everywhere, and not all schools have adequate ventilation, but where buildings are available and systems are good, this strategy offers multiple benefits including improved health infrastructure.

This approach aligns with recommendations in our earlier report advocating for seamless integration of child care with the education system. Health readiness, including ventilation quality, is one of many ways that co-location can improve outcomes compared to standalone facilities operating with minimal resources and oversight.

Building for the Future

New York’s child care expansion represents a multi-decade investment in infrastructure that will serve children for generations. Decisions made now about ventilation standards will shape health outcomes far into the future. Facilities built without adequate ventilation will require costly retrofits later, or they will continue to expose children and staff to elevated respiratory disease risk, undermining the goals of expansion.

The incremental cost of good ventilation in new construction is modest compared to the total project cost and the long-term benefits. For existing facilities, targeted investments in upgrades can be phased in over several years, prioritizing programs serving the most vulnerable populations and those operating in the oldest buildings. The key is establishing clear standards, committing resources, and providing technical support to ensure implementation.

Indoor air quality is not visible; unlike a broken window or peeling paint, poor ventilation is not apparent to parents or inspectors without measurement. This invisibility has allowed it to remain neglected in child care policy for decades. The COVID-19 pandemic made the consequences of poor ventilation impossible to ignore. New York has an opportunity to learn from that experience and embed air quality standards into child care expansion, creating a system that protects children from respiratory diseases today and is resilient to future threats.

In the next posts in this series, we will explore other critical elements of the built environment including facility safety, environmental hazards such as lead and mold, and emergency preparedness for climate-related and public health threats. Together, these built environment considerations, combined with workforce health supports and child health readiness measures, create the comprehensive infrastructure necessary for New York’s child care expansion to succeed.

Dr. Jay K. Varma is Senior Vice President and Chief Medical Officer at Fedcap, a large global nonprofit organization, and a Senior Health Fellow at the Community Impact Policy Institute. He is a physician-epidemiologist with extensive experience in infectious disease control, public health emergency response, and health systems strengthening across the United States and internationally. The full report “Protecting Health in Child Care Expansion” is available at the Community Impact Policy Institute.