Diesel exhaust is a major source of combustion particles that contribute to poor air quality nationwide. Since almost all school buses are operated with diesel engines, diesel engine exhaust can thus also be a source of concern, specifically with regard to exposure to children.
Diesel particulate matter (DPM) is a complex and unhealthy mixture of inorganic and organic carbon particles with adhered toxic substances and metals. The purpose of the study was to investigate the causes of school bus self-pollution and to document in-cabin diesel particulate matter exposures in buses retrofit with a variety of available particulate matter emissions control combinations. This is one of the first studies to report on the in-cabin benefits of retrofit technology.