Why Indoor Air Quality Matters for Mayors

While outdoor air pollution has long been recognized as a driver of poor health, most exposure to outdoor air pollution actually takes place indoors. According to the Environmental Protection Agency (EPA), pollutants can be up to two-to-five times more concentrated indoors than outside. Addressing indoor air quality (IAQ) is crucial for municipal leaders because Americans spend an estimated 90% of their time indoors. 

Poor IAQ can be caused by pollutants from both indoor and outdoor sources. For instance, fine particulate matter called PM 2.5 – the main component of outdoor air pollution and wildfire smoke – is so small that it can enter via tiny cracks and crevices, even when windows are closed. Indoor sources include synthetic products such as paint, textiles, and cleaners. Although “tighter” building envelopes may be more energy efficient, these spaces also tend to concentrate pollutants and have poor IAQ. 

Poor air quality negatively impacts health in both the short and long-term. Short-term effects include irritation to the eyes, nose, throat, and skin; coughing; headaches; dizziness; and fatigue. Many indoor pollutants – such as mold, dust, tobacco smoke, and particulate matter – can trigger asthma attacks or increase one’s risk for developing asthma. In the longer term, exposure to air pollution also raises the risk of heart disease, respiratory disease, and cancer. And, as seen with the COVID-19 pandemic, ventilation is crucial to minimize airborne transmission of infectious diseases like the flu.

Start With Schools: Improving IAQ to Enhance Performance and Reduce Absenteeism

Those who spend the most time inside are at the greatest risk  – including young children, older adults, and people with cardiovascular or respiratory disease. Children and adolescents are particularly vulnerable to pollution because their bodies are still developing and they breathe more air relative to their size compared to adults. Students, in particular, spend a significant amount of time indoors during the school day. 

Many school buildings lack sufficient air flow and many American public schools have outdated heating, ventilating, and air-conditioning (HVAC systems). Additionally, ventilation levels tend to fall short of national standards set by the American Society of Heating, Refrigerating and Air-Conditioning Engineers, ASHRAE. In fact, a 2020 report by the Government Accountability Office found that nearly half of all public school districts need to replace or update HVAC systems in at least half of their schools – 36,000 schools across the country.   

Improving IAQ in schools has numerous benefits. First, it can boost cognitive function, leading to higher test scores and better concentration and performance. The landmark CogFx study linked particle levels and cognitive function in an indoor setting and suggested that improved ventilation was associated with better performance. While this study was conducted among office workers, similar research among students has shown that better ventilation can improve test scores. 

“Office buildings influence worker cognitive function and productivity, and therefore can impact the bottomline performance of a company,” said Dr. Joseph Allen, Associate Professor at Harvard T.H. Chan School of Public Health, Director of the Harvard Healthy Buildings Program, and an investigator in the CogFx study. Likewise, Allen explained, “School buildings influence teacher and student illness rates, and student test performance.”

Better ventilation can also improve attendance by preventing mold growth and pollutant buildup that contribute to asthma and other illnesses. Research suggests that enhancing ventilation reduces respiratory symptoms as well as sick days among students and staff. The CDC estimates the economic cost of asthma at over $56 billion annually, including direct costs from hospital visits and indirect costs like missed days of school and work. 

Upgrading HVAC and other ventilation systems requires a substantial capital investment, but the benefits pay off in the long term. In another study, Allen and colleagues found that improving ventilation could lead to a $6,500 increase in employee productivity per year. At a larger scale, improving IAQ in offices could add as much as $20 billion annually to the U.S. economy, according to research from Lawrence Berkeley National Laboratory. While these figures come from office settings, the same principles apply to schools, where improved teacher and student attendance and performance could bring considerable educational and economic gains. 

Innovative State Policy Approaches 

California has taken the lead on improving IAQ in schools through several policy changes. The California Education Code 17661(d) requires public schools and state universities to install air filtration that meets minimum efficiency reporting values (MERV) 13 or higher, or the next best alternative. This is because MERV 13 filters capture about 80% of particles, including outdoor air pollutants, indoor sources like dust and new furniture, and pathogens. In his book Healthy Buildings, Allen points out that the most commonly used filter in buildings with a central ventilation system is a MERV 8 filter, which removes just 50% of PM 2.5. 

Additionally, the California Building Code (Title 24) recommends minimum ventilation of five air changes per hour, which aligns with guidance from ASHRAE. The California Department of Public Health notes that this can be achieved through a combination of HVAC upgrades, natural ventilation (if outdoor AQI is acceptable), and portable air cleaning devices. Minimizing the spread of respiratory disease and reducing absenteeism are explicit goals of this policy. While these recommendations are an important step toward improving IAQ, it’s worth noting that ASHRAE standards have historically aimed to minimize bodily odors, rather than improve health. The field of IAQ research is still relatively young, and standards from different agencies and professional associations vary in rigor, objectives, and enforceability. 

Many other jurisdictions have followed California’s example. For instance, Boston Public Schools has taken steps to improve IAQ by installing sensors in all classrooms and developing a comprehensive action plan. In 2024, Maryland created a new fund to address indoor environmental conditions in schools and Washington state allocated $45 million for grants to improve IAQ and energy efficiency. 

Following the COVID-19 pandemic, the EPA provided $34 million in grant funding to build capacity for IAQ improvement among K-12 schools in low-income, disadvantaged, and Tribal communities. This investment is needed because lower-income and Tribal communities face greater exposure to poor air quality and also tend to have lower budgets for infrastructure improvements. The University of Utah’s Clean Air Schools for U program is helping improve IAQ management and reduce greenhouse gases through assessments, pollutant monitoring, evaluation, and community engagement; this work will benefit urban and rural schools in Utah and Nevada, as well as the Northern Arapaho Tribe in Wyoming. 

Putting it Together: Practical Steps for Mayors

Investing in clean indoor air yields powerful health, productivity, and cost benefits for students, schools, and the broader community. Mayors should prioritize schools and universities as a starting point for these efforts, given that students tend to be more vulnerable to the harmful effects of air pollution. Plus, underfunded public school districts stand to reap considerable cost-savings by reducing absenteeism among students and staff. 

While mayors may or may not have direct responsibility for schools, they are well-positioned to engage in innovative partnerships and advocacy to address IAQ for students. For instance, Mayor Alex Morse of Holyoke, MA dedicated $950,000 of CARES Act funding to install HEPA filtration units in all district classrooms. In Los Angeles, CA, the Mayor’s Office of International Affairs partnered with local college students to analyze IAQ solutions. The student-led research calls for the city to partner with Los Angeles School District and private contractors for IAQ monitoring, filtration technology, and data collection in schools. This fall, Mayor Sadiq Khan of London invested £2.7 million ($3.5 million) to deliver HEPA filters to over 200 schools across the city. Research found a 27% to 68% reduction in PM 2.5 levels in the classrooms with HEPA filters compared to those without filters. 

Beyond schools, mayors can leverage sustainability initiatives to support HVAC optimization in public buildings and bolster electrification incentive programs for homeowners. For instance, the Piscataway Goes Green Initiative by Mayor Brian Wahler relies on grants, rebates, and the Investment Tax Credit (ITC) direct pay program to replace aging HVAC systems in public facilities. Likewise, Mayor Leirion Gaylor Baird of Lincoln, NE partnered with Lincoln Electric System to provide a heat pump incentive program to help residents reduce energy costs as well as carbon emissions. Heat pumps don’t involve combustion, thereby eliminating direct emissions of pollutants such as carbon dioxide, carbon monoxide, or nitrogen oxides. They also contain sophisticated filtration systems that filter air before it enters the home, further improving IAQ. In Boston, Mayor Michelle Wu’s Community Clean Air Grant funds several strategies to address air quality, including the provision of induction cooktops to Boston residents with gas stoves who are being treated for asthma as part of the Breathe Easy at Home program. 

Cities can also partner with school districts, nonprofits, and hospitals to prevent asthma and reduce absenteeism by enhancing ventilation. Mayors that prioritize workforce development could direct funding toward green infrastructure and HVAC training, with the potential to partner with high schools to support job training and preparedness. If a city funds or sponsors daycare or after school programming, municipal leaders could allocate some of the funding to improve ventilation in school buildings. For example, Mother’s Out Front East Boston used Mayor Wu’s Community Clean Air to install HEPA air filters and sensors in 27 daycare centers, benefitting over 250 children in a largely working-class, immigrant neighborhood. 

The benefits of addressing IAQ extend beyond improved health, reduced absenteeism, and economic gains. In fact, building design is one of the most cost-effective ways to reduce carbon. “Buildings account for 40% of energy consumption – and 70% in some cities – which means they are central to sustainability and energy conservation goals,” Allen said. “Buildings form the foundations of cities, and how well the buildings perform will determine how well a city performs.” By treating IAQ as essential infrastructure, mayors can protect public health, strengthen learning environments, and build more resilient, sustainable cities.