Wildfire smoke exposure and school absences in New York City Public Schools, 2011-2019

Climate change is intensifying wildfire frequency and severity across North America, degrading air quality in urban areas far from fire sources. While the direct health effects of wildfire smoke are well-documented, associations with educational outcomes remain poorly characterized. We conducted a time-stratified case-crossover study linking 2.11 million school-days from 1,443 New York City (NYC) public elementary, middle, and high schools over the 2011-2012 to 2018-2019 academic years with tract-level wildfire smoke fine particulate matter (PM_2.5) estimates, meteorological data, and school-level sociodemographic characteristics, using date-clustered inference to estimate associations between daily smoke exposure and absence rates. Stratified analyses examined variation by school level, and effect modification was tested by racial/ethnic composition, free/reduced-price lunch eligibility, English language learner status, and tree canopy cover. Economic impacts were estimated using the US Environmental Protection Agency Benefits Mapping and Analysis Program (BenMAP). Wildfire smoke was associated with higher absence rates on the day of exposure (rate ratio [RR] = 1.12; 95% CI: 1.02-1.23). Associations were statistically significant for elementary (RR = 1.18, 95% CI: 1.03-1.34) and middle schools (RR = 1.14, 95% CI: 1.03-1.27) but not high schools (RR = 1.06, 95% CI: 0.96-1.18). We did not detect significant effect modification by school-level demographic factors or tree canopy cover, though the limited number of unique smoke dates constrains subgroup power. Economic costs were $86.5 million annually for the NYC public school system (95% CI: $26.2-$150.5 million). These findings indicate heightened vulnerability among elementary and middle school students and support school-wide mitigation during smoke events, including improved air filtration, real-time air quality monitoring, and evidence-based activity modification protocols.