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 potentially 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.

Most discussion of special education has centered on the costs of providing mandated programs for children with disabilities and not on their effectiveness. As in many other policy areas, inferring program effectiveness is difficult because students not in special education do not provide a good comparison group. By following students who move in and out of targeted programs, however, we are able to identify program effectiveness from changes over time in individual performance. We find that the average special education program significantly boosts mathematics achievement of special-education students, particularly those classified as learning-disabled or emotionally disturbed, while not detracting from regular-education students. These results are estimated quite precisely from models of students and school-by-grade-by-year fixed effects in achievement gains, and they are robust to a series of specification tests.