Many regulatory agencies and school districts limit the idling of school buses while students enter or leave the vehicles, thereby restricting children's exposure to airborne diesel pollutants.
But concerns remained whether stopping and then restarting school bus engines might result in higher emissions of diesel pollutants than occur during continuous idling.
In the new study by John Kinsey and colleagues at the U. S. Environmental Protection Agency, diesel emissions from a limited number of school buses under both scenarios were measured. The researchers concluded restarting buses results in fewer emissions, so long as the vehicles depart quickly without any extended period of idling.
The study is to be published in the July 15 issue of the journal Environmental Science & Technology.