Electric school buses: healthier and more cost-effective?

The health and climate benefits of switching from diesel vehicles to electric ones are well established. Now, a study out of Boston, Massachusetts, has specifically examined the role of electric school buses in improving the health of humans and the planet.

The researchers, from the Harvard T.H. Chan School of Public Health, found that replacing diesel school buses with electric school buses may yield up to US$247,600 in climate and health benefits per individual bus. Their study has been published in Proceedings of the National Academy of Sciences.

There are about half a million school buses in use in the US and a substantial portion are older diesel buses. Despite diesel buses being highly polluting, switching to electric buses can be a difficult decision for local, state and federal officials given their expense and the lack of data on their health impact.

“Research on air pollution and climate change should strive to quantify health benefits,” said senior author Kari Nadeau, John Rock Professor of Climate and Population Studies and Chair of the Department of Environmental Health.

“Our findings can inform policymakers that greenhouse gas emissions and air pollution are reduced by implementing solutions like electric vehicle use. Our data offer strong evidence that accelerating the ongoing transition to electric school buses will benefit individual, public and planetary health.”

To quantify how diesel and electric school buses impact the climate, the researchers measured the amounts of carbon dioxide emitted from diesel school bus tailpipes as well as the CO₂ produced by electric school buses’ electricity generation and battery production. To assess the buses’ health impacts, the researchers compared how their respective emissions contribute to fine particulate air pollution (PM2.5), which is linked to adult mortality and the onset of childhood asthma.

The study found that replacing an average diesel school bus in the US fleet in 2017 with an electric one resulted in US$84,200 in total benefits per individual bus. Each electric school bus emitted 181 fewer metric tons of carbon dioxide than its diesel counterpart, amounting to US$40,400 worth of climate benefits. Additionally, each electric school bus resulted in US$43,800 in health savings, due to less air pollution and reduced rates of mortality and childhood asthma.

The study also found that electric school buses’ health benefits vary depending on location and the age of the diesel bus being replaced. Large metropolitan areas — defined as those with a population of more than one million — derive the most significant health benefits from electrifying fleets of school buses, given the larger number of people whose air quality is improved. The researchers calculated that, in a large city, replacing a 2005 diesel school bus with an electric bus would achieve US$207,200 in health benefits per bus.

“In a dense urban setting where old diesel buses still comprise most school bus fleets, the savings incurred from electrifying these buses outweigh the costs of replacement,” Nadeau said. “Not to mention how the tangible benefits of electric school buses can improve lives — especially for racial minorities and those living in low-income communities who are disproportionately impacted by the everyday health risks of air pollution.”

Nadeau and her co-authors noted that the study did not analyse how electric school buses impact children’s exposure to in-cabin air pollution while riding the bus. Additional research into this topic could further inform policy decisions.

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