2024 Yes https://www.healtheffects.org/system/files/adar-rr-221-report-accessible.pdf Adar, Sara D. North America Experimental Epidemiology Study Modeling Students Elementary (K-5) Middle/Jr High (6-8) High School (9-12) Particulate Matter (PM) Absenteeism Test Performance Respiratory symptoms This randomized trial evaluated the US EPA’s School Bus Rebate Program. Replacing old buses improved attendance, test scores, and reduced PM2.5, providing evidence of educational and health benefits from cleaner school transportation.