Schools invest in curriculum, staffing, and technology to improve learning outcomes. The air in those classrooms matters just as much.
As autumn approaches and schools are preparing to begin sessions, air quality can be a hidden deterrent, impacting student learning and engagement. Depending on school location and regional environment, airborne pollutants could be produced at elevated levels and invade indoor classroom air. Protecting student health through clean indoor air secures productive classrooms.
By understanding the different types of classroom pollutants, associated health implications, and joint parent-educator clean air efforts, students can breathe healthier air with no learning disruptions.
What airborne pollutants can be found in classrooms?
School location and the surrounding outside air quality environment can have a great impact on various levels of airborne pollutants. For instance, daycares located in populous urban cities may experience heightened levels of traffic emissions, while schools neighboring rural areas could see increased wildfire risk and allergen activity. These air quality events can harbor a wide range of unhealthy pollutant particles, such as:
- Smoke
- Pollen
- Pet dander
- Gases
- Odors
- Volatile organic compounds (VOCs)
- PM2.5, particulate matter down to 2.5 microns in size
-
PM10, particulate matter down to 10 microns in size
With multiple students per class and multiple classrooms within schools, airborne pollutants are easily stirred up and circulated from one individual to the next throughout the day. According to Harvard University, synthetic carpets and dyes schools commonly use have been known to release airborne chemicals, impacting student health (1). CO2, an odorless invisible gas, can also be released through vehicle exhausts in neighboring streets, wildfire smoke, and indoor building vents.
Air quality can be infectious as well. Bacterial and viral particles can pass between individuals and cause elevated risks for illness within larger crowds. Airborne viruses, such as SARS- CoV-2 and influenza, can spread through close-contact exposure, especially in stale indoor environments. SARS- CoV-2 is the virus that leads to the COVID-19 disease.
Students can also carry allergens and pollutants into classrooms on their clothing. Cat dander in particular travels easily from pet-owning homes to school. One study found that cat allergen hitchhikes on students' garments, disperses into classroom air, and is abundant even in classrooms where no cat has ever been (2).
How does air pollution impact learning?
Air pollution impacts critical areas of student learning, including attendance levels, cognitive function, and test scores. In a survey of studies mostly drawn from urban schools in countries including the U.S., the UK, Sweden, and Brazil, it was found that long-term exposure and higher peaks in pollution could impact school performance and outcomes. This was especially true in schools affected by socioeconomic factors (3).
A paper published in 2025 found that a 10 µg/m3 increase in PM2.5 exposure in an urban California school district caused a 5.7% increase in full-day student absences and a 28% increase in office referrals over a three-day window (4). The same rise in pollution levels also increased teacher absences due to illness by 13.1%.
A study published in the European Journal of Pediatrics reviewed cognitive function in school age children at schools affected by traffic-related pollutants (5). Analysis found that exposure to these pollutants resulted in lower verbal comprehension in girls, while boys experienced a reduced working memory.
CO2 buildup in poorly ventilated classrooms can also impair learning. A 2015 study conducted by Harvard University found that cognitive function scores dropped by 15% when indoor CO2 reached approximately 950 ppm, and by roughly 50% at 1,400 ppm, levels commonly found in crowded, under-ventilated classrooms (6). A 2025 study found that even within relatively low CO2 ranges, students in classrooms with lower concentrations consistently scored higher on cognitive tests, with peak CO2 exposure showing the strongest effect on performance. (7).
Between 2001 and 2018, researchers tracked 2.8 million public school students in North Carolina. This large representation of students spanning the student’s entire time in public schools confirmed that exposure to PM2.5 played a negative role in standardized test scoring (8).
How airborne pollutants impact adolescent health
Aside from bacterial and viral illnesses, airborne pollutants have been linked to elevated health risks and symptoms that disrupt personal learning and productivity. A 2019 study found that even short-term exposure to airborne pollutants increased the risk for adolescent youth to be hospitalized for mental health concerns, such as intense stress, sadness, anxiety, and harmful thoughts or behaviors (9).
Air pollution has a demonstrated, strong impact on children’s lung development. Children living London were found to have much smaller lungs than those of their peers living in Luton, England due to exposure to traffic-sourced air pollution. However, a 2026 study found a decline in childhood lung impairment following the establishment of London’s Ultra Low Emission Zone (ULEZ). Children ages 6-9 years old in London were found to have seen accelerated lung growth compared to the control group in Luton. The London children also experienced an improvement in clinically impaired lung function, dropping from 14% to 9%.
Poor air quality can have prolonged effects on developing children and sensitive groups, exacerbating pre-existing symptoms and conditions. Another 2019 research study discovered a link between school absences and asthma, specifically noting urban locations and pollution (10). In many schools are located to close to major roadways. In the U.S. alone, almost 8,000 public schools are within 500 feet of highways, truck routes, and other traffic-heavy roads, elevating PM2.5 levels within the region of these learning spaces (11).
School staff health is also impacted by airborne pollutants. Teachers and staff may experience short- and long-term health problems from poor indoor air quality, ranging from coughing, sneezing, and headaches to more serious health outcomes, like respiratory tract infection and disease and asthma (12).
How to reduce exposure to allergens and pollutants in schools
Air cleaning tools provide optimized support in minimizing airborne pollutant exposure and contagious spread of viral particles. HyperHEPA air purifiers contain maximized filtration, capturing 99.5% of ultrafine pollutants down to 0.003 microns in size, such as smoke, pollen, and particulate matter. Extended runtimes and automated air cleaning devices can be effective for learning spaces as airborne pollutants can disrupt teaching at any time.
Schools can join the Clean Air Schools program to help foster safer, healthier learning environments for students. In California, home to the largest number of Clean Air Schools in the country, some students are already benefitting from cleaner air. A pilot study by the South Coast Air Quality Management District (SCAQMD) demonstrated that low-cost, high efficiency HVAC filters removed on average 90% of ultrafine particles and diesel particulate matter from indoor air in three schools near refineries, freeways, and industrial facilities.
Cleaner indoor air means reduced absenteeism as well. Through a combination of source control, proper ventilation, and effective air filtration, schools can increase classroom attendance. This can mean increased school funding where funds are linked to lowered absenteeism and better Average Daily Attendance (ADA) (13).
Socio-economic disadvantaged and pollution impacted schools can also apply for grant funding, through the Clean Air for Kids initiative from the Foundation for Clean Air.
What can schools do
School staff and district officials can make an impactful difference in student health between every classroom with the proper integrated air cleaning technology and awareness. Implementing advanced school-wide filtration alongside air quality event awareness can help protect student and staff well-being, such as:
- Join the Schools4Earth program
- Become a Clean Air School
- Apply for Clean Air for Kids funding if applicable
- Open school-wide windows and doors for maximized ventilation when the air is clean
- Host district meetings or open inquiry drop boxes to collect student health questions and air quality concerns
- Routinely sanitize commonly used surfaces
- Avoid scented chemical cleaning aerosols
- Open classroom windows for maximized airflow ventilation, when the outdoor air is clean
- Incorporate air quality monitoring and pollutant effects into educational lessons plans
- Routinely sanitize commonly used surfaces
- Avoid scented chemical cleaning aerosols
- Open classroom windows for maximized air flow ventilation
- Incorporate air quality monitoring and pollutant effects into educational lessons plans
What can parents do
Parents, relatives, and community members can take initiatives and plan ahead for students to transition smoothly and safely into new indoor environments. Practicing air-conscious lifestyle choices alongside at-home filtration ensures students feel prepared and aware of air quality conditions, including:
- Ensure schools are equipped with indoor and outdoor air quality monitors to spread awareness
- Keep KN95 masks on hand during wildfire smoke events
- Donate air purification devices to classrooms in public schools
- Routinely sanitize school backpacks and clothes that can track in pollutants
- Discuss specific air quality or health needs with educators to ensure proper childcare
- Drive an electric vehicle or utilize school bus drop-offs to limit traffic emissions
- Attend school district meetings to contribute to air quality improvements
Clean air preparation and lifestyle choices for students can help build environmental awareness and secure healthy breathing conditions both in school and at home.
The takeaway
Schools should feel like safe, productive learning spaces no matter the location or city it resides in. Securing clean air quality and practicing air-conscious choices can be impactful steps to creating a healthy environment for students this upcoming school year. With the Clean Air School certification with monitoring tools, air quality can be implemented within daily schedules or even educational lesson plans.
By leveraging air quality data, technology, and filtration, student health protection can be maximized and fit seamlessly into environmental education.
