Attendance Benefits of the EPA’s School Bus Rebate Program: A Randomized Design

BACKGROUND AND AIM: While buses remain the safest school transport from an accident perspective, older buses can expose students to high levels of diesel exhaust. Since these exposures adversely impact health and can cause missed school, the US Environmental Protection Agency (EPA) has spent millions of dollars to transition school bus fleets to cleaner vehicles. 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. METHODS: We used classical intent-to-treat analyses for randomized controlled trials to compare changes in school district attendance rates after vs before the 2012-2017 lotteries by funding selection status. We evaluated heterogeneity of effect by quartiles of estimated ridership and model years (MY) of the replaced buses since emissions standards have strengthened over time. RESULTS: Within our analytical sample, 383 of the 2,816 EPA applicants were selected for funding. We found that districts selected for funding had, on average, a 0.06 percentage point (pp) higher attendance rate in the year after the lottery (95% CI: -0.01, 0.13) compared to unselected districts. Impacts were larger for districts with the highest estimated ridership on applicant buses (0.14 pp; 95% CI: -0.05, 0.32) and who replaced the oldest buses (pre-1990 MY replacement: 0.45 pp; 95% CI: 0.26, 0.65). In the first year after the funding lotteries we estimate there were 350,000 (95% CI: -70,000, 770,000) additional student-days of attendance due to these EPA funds. Extrapolation of our results suggests that replacement of all pre-2000 MY buses nationwide would lead to 1.3 million additional student-days of attendance each year (95% CI: 250,000, 2,400,000). CONCLUSIONS: We find evidence that the EPA’s School Bus Rebate Program has improved student attendance, especially in districts that had high levels of ridership on the impacted buses and removed the oldest buses.