Air Filters, Pollution, and Student Achievement
利用美国史上最大天然气泄漏事件中空气过滤器安装的自然实验，发现教室安装过滤器使考试成绩提高0.1-0.2个标准差，且效果源于去除常见污染物。
<h3>Abstract</h3> 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 0.1-0.2<i>σ</i>. 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.