Air Filters, Pollution, and Student Achievement

This paper identifies the achievement impact of installing air filters in classrooms for the first time. I leverage a unique setting arising from the largest gas leak in U.S. history, whereby the offending gas company installed air filters in every classroom within five miles of the leak (but not beyond). Using a spatial regression discontinuity design, I find substantial improvements in student performance: air filters raised mathematics and English scores by 0.20σ. Natural gas was not detected inside schools, indicating that the filters improved air quality by removing common pollutants. On that basis, these results should apply more widely.