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New study finds unhealthy air inside school buses
Oct. 17, 2003 — Vehicle pollution inside many California school buses may be worse than levels found in roadway air, a California Air Resources Board study has found.
CARB said this study of children’s exposures while riding school buses was the most comprehensive study of its type ever conducted. Pollutant concentrations were measured on board buses of various ages and types, driven over actual bus routes in Los Angeles.
The Children's School Bus Exposure Study was conducted to characterize the range of children's exposures to diesel vehicle-related pollutants and other vehicle pollutants during their commutes to school by diesel school buses.
The study, conducted by researchers at the University of California Riverside and Los Angeles campuses, measured pollutant concentrations inside five conventional diesel school buses over actual school bus routes in Los Angeles.
For comparison, a diesel bus equipped with a particulate trap and a bus powered by natural gas were also included. Other goals of the study were to determine what factors influenced the highest exposures.
Major Findings:
Measurements indicated that for some buses, significantly higher exposures of vehicle-related pollutants occurred during the bus commutes than roadway pollutant concentrations alone would indicate.
The high commute concentrations were a varying function of several influences:
- the high concentrations of pollutants already present on roadways, especially if traffic was heavy;
- the direct influence of other vehicles being followed; and
- the contribution of the bus’s own emissions. The extent of a bus’s own contribution to these high concentrations appeared to be highest when windows were closed for the older and/or dirtier diesel buses, but bus-to-bus variability was high.
Recomendations from this report include:
- Reducing school bus-related exposures by assigning the newest and cleanest buses to the longest routes.
- Avoiding caravanning of buses through staggered departure times.
- Replacing conventional diesel school buses with natural gas-powered or particulate trap-equipped buses.
Related Clean Air Agency resources:
