A new study outlined the dangers of air pollution near schools, and showed that air quality could be greatly improved if idling school buses simply turned off their engines.

"The concentration of air pollutants near schools often significantly exceeds background levels in the community, particularly when idling school buses are present," Patrick Ryan, the Children's researcher who was the lead author of the study, said, the Cincinnati Enquirer reported via USA Today. "Anti-idling campaigns are frequently attempted to improve air quality, but until now, no one has evaluated how effective they are."

Researchers took air samples around four Cincinnati public schools. They took the samples as the school buses pulled up in the morning, and as they left in the afternoon, a Cincinnati Medical Center news release reported.  They also tested the air in surrounding communities.

The air quality measurements at three of the four schools "exceeded community background levels." The schools with more buses were found to show the greatest difference.

A campaign was launched to bring awareness to the issue. The effort included education on the subject for bus drivers and parents, a no-idling pledge, signs outside of the schools, and even a student-created movie.

After  the campaign local air quality was tested again. At the school that had the most buses (39) background noise particulate matter had decreased by 76 percent and elemental carbon decreased as well by 63 percent.

"Anti-idling campaigns are frequently attempted to improve air quality, but until now, no one has evaluated how effective they are," Ryan, lead author on the study, said in the statement. "The results of this study demonstrate, for the first time, that not idling is a simple and effective policy that can improve air quality at schools, especially schools with a large number of buses."

"We have to keep reinforcing the habits," Ryan said, the Cincinnati Enquirer reported.