The latest in a series of controversial studies examining diesel fumes and children's health, the study placed ultra-sensitive monitors on children and recorded air quality readings throughout the day.

For short periods of time, the research showed exhaust levels 5 to 10 times higher than government standards, said the study's lead author Dr. John Wargo, Yale professor of risk analysis and environmental policy.

"Levels of fine particles and black carbon were higher under certain circumstances: when buses were idling with doors or windows opened; when buses moved through intense traffic; when buses followed other diesel vehicles; and especially when buses were queued to load or unload students while idling. Particle and black carbon levels on buses powered by natural gas were not distinguishable from background levels," according to the report.

"There is no known safe level of exposure to diesel exhaust for children," said Robert LaCamera, M.D., Clinical Professor of Pediatrics at the Yale School of Medicine and a reviewer of the study.

Released on "Good Morning America," the study was portrayed as a Yale University product. However, according to an Environment and Human Health press release, EHH commissioned and financed the study. The University of Connecticut's Environmental Research Institute conducted the study's air quality monitoring.

According to Charley Gauthier, Executive Director of the National Association of State Directors of Pupil Transportation Services, school transportation industry officials are eager to conduct a peer review of the EHH study, questioning the organization's political agenda.

"Let's wait and make sure we understand everything before we make decisions that affect health of our children," Gauthier said.