Reducing school bus emissions has been shown to have numerous benefits for the environment, but a new study from the University of Michigan and the University of Washington has found another surprising upside to making school buses more eco-friendly; students are more likely to come to class.
The study is believed to be the first to gauge the individual impact the federal mandate to reduce diesel emissions has had on students.
The researchers say the results show a clear link between improved health from decreased school bus emissions and reductions in absenteeism, especially among children with asthma.
According to the report, published in the American Journal of Respiratory and Critical Care Medicine, shifting to ultra-low sulfur diesel fuel reduced a marker for inflammation in the lungs of 16% of children studied, and 20% to 31% among children with asthma.
“The national switch to cleaner diesel fuel and the adoption of clean air technologies on school buses lowered concentrations of airborne particles on buses by as much as 50%,” said Sara Adar, the study’s lead author and assistant professor of public health at the University Of Michigan School Of Public Health. “Importantly, our study now shows measurable health improvements from these interventions, too.”
The U.S. Environmental Protection Agency required the production of cleaner fuel and set stricter emissions standards for diesel vehicles purchased after 2006. The EPA also offered funding for fleets to retrofit, replace, or repower older diesel school buses.
For the study, researchers followed 275 Washington state students who rode buses to and from school, before and after their districts made the change to cleaner fuels and buses. The researchers also measured air pollution during 597 trips on 188 school buses from 2005 to 2009.
Children involved in the study also underwent monthly checks for lung function and inflammation, and researchers were given data on absenteeism from participating schools.
Over the period of four years, two districts altered buses with emissions devices. Some were fitted with diesel oxidation catalysts or closed crankcase ventilation systems, and all buses changed to ultra-low sulfur diesel or biodiesel. According to the researchers, these fuels are projected to reduce particle generation by up to 30%.
The report shows that children in the district missed 3.1 school days over nine months on average, but after adopting low-emission fuels the schools saw an 8% drop in absenteeism. The researchers also found a 6% drop in absenteeism associated with riding a bus fitted with a diesel oxidation catalyst.
After crunching the numbers, the researchers ultimately claim changing all school buses across the nation to low-emission options would reduce absenteeism by up to 14 million days per year across the 25 million school-bus riding children in America.
“Our research also suggests that children riding buses with cleaner fuels and technologies may experience better lung development as compared to those riding dirtier buses,” Adar said.
