Does Pollution Increase School Absences?
利用德克萨斯州39个大学区的小学和初中行政数据，结合环保署空气质量数据，用三重差分法控制混杂因素，发现即使低于联邦标准的一氧化碳水平也会显著增加学生缺勤，过去二十年一氧化碳下降带来了显著健康收益。
Abstract—We examine the effect of air pollution on school absences using administrative data for elementary and middle school children in 39 of the largest school districts in Texas merged with air quality information maintained by the Environmental Protection Agency. We address poten-tially confounding factors with a difference-in-difference-in-differences strategy that controls for persistent characteristics of schools, years, and attendance periods. Of the pollutants considered, we find that high carbon monoxide (CO) levels, even when below federal air quality standards, significantly increase absences. Our results suggest that the substantial decline in CO levels over the past two decades has yielded economically significant health benefits. I.