Clean Fuel News

A Georgia State study says diesel school bus fumes drive down test scores

Originally posted by Ty Tagami | July 18, 2019 | Atlanta Journal-Constitution | Original Article

For decades, schools have put their students on buses that belch diesel fumes, despite mounting evidence about the ill effects of the exhaust, especially on young, developing lungs.

Now, as parents consider whether to sign up their children for the bus ride to school in a few weeks, new research is drawing a direct line between those fumes and poorer classroom performance. Even before Georgia State University released its report, lawmakers and school transportation directors felt something needed to change. There had been plenty of prior research linking diesel exhaust to allergies, asthma attacks and lung cancer.

“Nothing’s going to be healthy about sitting over an exhaust pipe,” said Rep. Terry England, R-Auburn. The chairman of the House Appropriations Committee tucked $1.8 million into the 2020 state budget to help school districts buy alternative fuel buses. That is in addition to an amendment to the current-year budget that added $1.2 million for the same purpose.

The alternative fuel of choice for Georgia schools is propane. Those buses cost $16,000 more than diesel buses, and the grants cover half of the surcharge. It’s helped 17 school districts buy 156 propane buses this fiscal year. Overall, though, it is a small financial commitment for a state with 180 school districts, where the vast majority of school buses are still powered by diesel.

New research from Georgia State University emphasizes the stakes. It’s been two decades since California concluded that microscopic diesel exhaust particles were enough of a risk to human health to justify dialing back emissions. The new Georgia State study says diesel buses also undermine the very mission of schools.

It links dirtier bus exhaust to worse academic performance. Researchers compared the standardized test scores of students in Georgia school districts where more than 2,600 buses had been retrofitted with exhaust-scrubbing systems against test scores in districts lacking the upgrades.

“Students do better on English tests if they have cleaner air,” said Daniel Kreisman, an assistant professor of economics who co-authored the study. “It’s not a huge effect. It’s not like they’re going to skip two grades, but they definitely scored better.”

It is an important study because it is the first to directly link bus fumes to school performance, said Sara Adar of the University of Michigan. The associate professor of epidemiology was not involved in the Georgia study, but did work on a different one several years ago that tracked students who were switched from buses with dirty exhaust to those with cleaner systems.

“We found that kids were far less likely to miss school when they were riding cleaner buses than when they were riding dirty buses,” she said. There is new evidence that exhaust particles can get into the brain, she said. “Those older, dirtier buses are ones we should get off the road.”

The exhaust system upgrades cost $5,000 to $10,000, which Kreisman and his colleagues argue is a pittance compared to the long-term return for society when students do better in school. The bus overhauls in their study occurred between 2007 and 2015. Since then, more school districts have been opting to bypass diesel altogether, replacing their fleets with buses powered by propane, the gas burned by backyard grills and camping stoves.

Justyne Lobello, spokeswoman for iconic school bus maker Blue Bird Corp., said propane buses have the cleanest school bus combustion engines on the market. “What comes out of the tailpipe is water vapor, essentially,” she said.

Half the school buses in Georgia are Blue Birds. The Fort Valley company says 627 of its propane buses are on the roads in the state. That’s a fraction of the 15,142 diesel buses, but the alternative fuel trend is accelerating. This year, Blue Bird sold 336 diesel buses to Georgia schools versus 264 powered by propane.

Student health is surely a concern for school districts, but the biggest driver may be economic: Propane buses are less expensive to run, with cheaper fuel, fewer moving parts and less crud to soil the engines.

Read the full article on the Atlanta Journal-Constitution website