Why clean air
The missing input where children learn and grow: clean air
The biggest unmeasured input in education is the air. Schools and child care programs are licensed and inspected for safety, food handling, and building conditions, and are increasingly tested for lead in drinking water, yet most have never monitored the air children breathe.
The case for clean air
What the evidence shows
Increasingly, the evidence is showing that this is holding children back from achieving their fullest potential:
- Clean indoor air matters from infancy through adolescence. Children’s brains and lungs develop through the teenage years, and a review of 40 brain-imaging studies of children from birth to age 18 links air pollution to differences in brain structure and function.
- In early childhood, exposure is high and the stakes are early. Studies across three continents associate higher fine-particle exposure in early life with lower childhood IQ. The years before kindergarten are when children are both most vulnerable and spending long hours in care.
- In K-12, air quality shows up in learning, attendance, and behavior. In U.S. schools, cleaner air has been linked to higher test scores, fewer absences, and fewer discipline incidents (see below). These are the outcomes schools already work hardest to improve.
- Clean air improves attendance and keeps children healthier. In a randomized trial involving more than 2,000 children, classroom air cleaning reduced absences by 12.5%, with the largest benefits among students who had been missing the most school. In a Helsinki study of a cluster of daycare centers, room air cleaners cut new infections by 18% (95% CI 2–31%), from 0.95 to 0.78 per child per month.
- Clean air improves learning. Even low levels of air pollution below federal standards have been found to reduce learning and student performance gains by nearly 20%. Another study found student math and English scores rose by 0.1–0.2 standard deviations after introducing air purifiers, an unusually large gain for an intervention costing roughly $1,000 per classroom.
- Clean air improves long-term health. Fine particulate pollution penetrates deep into the lungs and enters the bloodstream. A growing literature links it to asthma, cardiovascular disease, cognitive development, and other outcomes we spend billions trying to improve downstream. Young children are more vulnerable; they breathe more air per pound of body weight than adults, and their lungs and brains are still developing.
- Poor air quality is even connected to poor behavior. Air pollution has been associated across multiple studies with increased school discipline incidents, including fighting, defiance, and interpersonal conflict.
- Pollution outside follows students into their schools and early childhood care settings. Students at a school downwind of a major highway have lower test scores, more absences, and more behavioral incidents than at comparable upwind schools. Wildfire smoke during the school year has lowered test scores across thousands of U.S. school districts, and low-income communities lose the most.
- “Go inside” isn’t enough on bad air days. When pollution or smoke spikes, the standard advice is to stay indoors, but indoor air comes from outside. In one study, 71% of K12 campus buildings went over the daily air quality limit during a smoke event, including buildings with upgraded HVAC filters.
- Kids spend most of their day indoors. People spend about 90% of their time indoors, and children spend roughly half their waking hours in classrooms. Young children in child care spend about 30 hours a week there, roughly a full-time job, almost entirely indoors.
- Interventions work. In-room filters have cut classroom particle levels by 77%; a few dollars per student per year buys a large drop in what kids actually breathe, starting the day the filters go in.
This is not a ten-year facilities program. HVAC settings changes and filter upgrades can make a difference inexpensively overnight. To improve air quality further, modern in-room filtration can dramatically reduce airborne particles with no construction, no HVAC replacement, no new staff, and nothing asked of teachers. An excellent filtration system can cost as little as $5–10 per student per year.
That combination is rare in education: a solution to a large problem that’s inexpensive, imposes little administrative burden, and directly benefits students, parents, and teachers. Leadership can begin deploying cleaner air this school year, and see effects on exposure, attendance, and learning within months.
More on why clean air
Get in touch
To learn more about Clean Air Capitals and the 2027 Cohort, write to us at [email protected].