Can School Bus Emissions Retrofits Improve Student Test Scores?

Emissions from the tailpipe of a school bus.
Soot emanates from a school bus tailpipe.

A new Georgia State University study claims that retrofitting school buses with emissions-reduction equipment can not only save money and improve air quality but also help classroom learning.

“School Bus Emissions, Student Health and Academic Performance” examined school bus retrofit programs in Georgia and compared them with student health and academic performance.

Report co-author Garth Heutel, an associate professor of Georgia State’s Andrew Young School of Policy Studies, told School Transportation News the study was the first of its kind to review retrofitting and its possible effect on student academic performance.

Huetel, Assistant Professor Daniel Kreisman and graduate assistant Wes Austin analyzed student test score data from the 2006 through 2017 school years and found better scores in districts that retrofitted their school buses. Gains were confirmed for English test scores, but there was only mixed evidence on the math test scores. School districts also saw an improvement in child respiratory health outcomes.

The researchers studied data from four different types of emission retrofits. The most used filter, the diesel particulate filter, captures most of the emissions that leave the tailpipe. It was found to be the best emissions-reduction tool on older buses.

The study advised that retrofitting school buses does improve academic achievement. The authors concluded that installing retrofit equipment, while a less glamorous approach to saving money is a cost-effective solution to attaining higher test scores, when compared to reducing class sizes or other interventions.

“So, it was three to six times more expensive for class size reductions in this previous study than what we’re finding with the retrofits,” Heutel explained. “ The takeaway from that is, if you are a school district with $1 million to spend and you want to improve test scores, it seems like bus retrofits give you more bang for your buck, compared to these other alternative measures.”

While the study didn’t include electric or alt-fuel buses, Heutel said the projections can gauge the possible increase in emissions reductions.

“But to our understanding, the electric buses are pretty expensive now,” Heutel concluded. “These retrofits were pretty cheap—an average of $8,000 per retrofit. So getting some pretty high test and health score benefits for a relatively low-cost intervention … seems like a good idea.”

This article also appears in the June issue of School Transportation News magazine.