Abstract
Abstract This paper identifies the impact of installing air filters in classrooms for the first time. To do so, 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 test scores by 0.1-0.2σ. Natural gas was not detected inside schools, implying that the filters improved air quality by removing common pollutants and so these results should extend to other settings.