Association for Public Policy Analysis & Management

Prior work shows that air pollution affects cognitive performance, and school bus diesel emissions meaningfully contribute to this exposure for school-age children. I exploit variation in the timing and location of 28,000 school bus engine retrofits or replacements across the US from 2008-2016 to test how reducing diesel emissions affects student test scores. I also incorporate satellite-based PM 2.5 measurements from the Atmospheric Composition Analysis Group to provide the first evidence that these engine retrofits significantly reduce ambient atmospheric pollution levels, suggesting potentially large spillover benefits from the retrofits separate from the student test score improvements. Finally, I ask how the cost of retrofitting these busses, approximately $233 million over 209 unique grant cycles, compares to the monetized benefits of the observed test score improvements.