Randomized design evidence of the attendance benefits of the EPA School Bus Rebate Program

Approximately 25 million children ride buses to school in the United States. While school buses are the safest school transport from an accident perspective, older buses often expose students to high levels of diesel exhaust. Because these exposures can adversely impact health, which may lead to more missed school, the US Environmental Protection Agency (EPA) has spent millions of dollars to hasten the transition of school bus fleets to cleaner vehicles. Here, we leveraged the randomized allocation of the EPA's 2012-2017 School Bus Rebate Program funding to causally assess the district attendance impacts of upgrading buses. Districts randomly selected for funding had greater attendance improvements after the lottery than unselected districts, resulting in over 350,000 estimated additional student days of attendance each year (95% confidence interval = -70,678 to 772,865) due to the use of EPA funds. Attendance improvements were greatest when the oldest buses were replaced and for districts with high ridership on applicant buses. Extrapolating our results nationwide, we expect that the replacement of all pre-2000 model year school buses would lead to more than 1.3 million additional student days of attendance per year (95% confidence interval = 247,443 to 2,406,511). Given the importance of attendance to educational success, we conclude that increasing the pace at which older, highly polluting buses are replaced positively impacts student attendance.