Wildfire Smoke Days Climb at U.S. Schools, Childcare
Families with children in school or childcare now face more smoke days, and some buildings hold more indoor particles than the air outside.
Updated on Nov. 3, 2026 in Asthma
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A new study found that wildfire smoke days at U.S. schools and childcare centers rose sharply between 2006 and 2023. Researchers reported that some school and childcare buildings had higher indoor fine-particle levels than nearby outdoor air on smoke days, and the findings appear in the Dec. 1 issue of Environmental Research.
Why it matters
For families of school-age children and young kids in care, more smoke days means more time when fine particles can reach indoor spaces where children spend most of their weekdays. Because wildfire smoke can carry PM2.5 particles deep into the lungs, the rising frequency raises a practical question about how well school and childcare buildings protect against outdoor air.
The study analyzed air quality data from more than 100,000 schools and 130,000 childcare centers across the country, and compared indoor and outdoor air at 71 West Coast facilities. Results show the number of smoke days rising sharply over nearly two decades, though the indoor comparison covered only a limited set of buildings.
The players
Environmental Research
A peer-reviewed scientific journal that publishes research on environmental health and pollution exposure.
The details
Wildfire smoke can carry fine particles known as PM2.5, which are small enough to penetrate deep into the lungs. In the indoor comparison, some schools and childcare centers recorded higher indoor PM2.5 concentrations than nearby outdoor measurements on smoke days, meaning a building does not automatically filter out smoke simply by being indoors. The findings suggest that buildings can concentrate exposure rather than block it, depending on how they are ventilated and sealed.
Timeline
2006: Baseline year, when schools averaged about seven smoke days and childcare centers about nine.
2023: Latest year in the study, when schools averaged 54 smoke days and childcare centers averaged 112.
Dec. 1: The study appears in the issue of Environmental Research.
Health Landscape
Asthma and respiratory health specialists have long tracked how poor outdoor air affects children, and this study adds a measured national trend in smoke exposure in the settings where children spend most of their time. The finding shifts attention from outdoor air quality alone toward whether school and childcare buildings can keep indoor particle levels lower than the air outside.
If your child attends a school or childcare center with frequent smoke days, it is worth asking the facility how it handles air filtration and ventilation during wildfire events. Families of children with asthma may want to discuss smoke-day plans with their child's doctor.
The takeaway
The rising count of smoke days in schools and childcare centers means indoor air is becoming a bigger part of children's exposure to wildfire pollution. Ask your child's school or childcare provider how they manage air filtration on smoke days.
Further reading
For more on how respiratory conditions like this are managed, explore our Asthma coverage.
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