Wisconsin Biodiesel in

School Bus Fleets

Children are most susceptible to health consequences of air pollution. Childhood asthma is on the rise and is, among chronic conditions, the leading cause of absenteeism in school

Diesel exhaust has been identified as one such source of air pollution that greatly affects our health., and nowhere is this more critically realized than in the exhaust encountered by schoolchildren in their daily commutes via school buses powered by diesel engines.

Diesel exhaust is a complex mixture of gases and particulate matter (commonly known as “soot”). Tests conducted on conventional school buses along actual bus routes found that diesel exhaust routinely penetrated the school bus cabins from the tailpipe and the engine compartment through the front door of the bus. Over the course of these routes, particulate matter (PM) increased to levels multiple times that of outdoor ambient conditions deemed acceptable by EPA standards (PM2.5 NAAQS). During queuing – where buses are parked closely end-to-end with front doors open – rapid build up of particulate matter was measured within the bus cabin.

Biodiesel is an alternative fuel source that can help address some of the health concerns created by diesel emissions from school buses. (See Wisconsin Biodiesel in Air Quality Remediation flyer published by WBA). The EPA has identified biodiesel as a “cleaner fuel” that is recommended for use to reduce the harmful gases and PM that are emitted by school buses. (See http://www.epa.gov/cleanschoolbus/)

The Wisconsin Biodiesel Association supports the EPA “Clean School Bus USA”initiative and has sponsored this effort locally to reduce the threat to Wisconsin childrens’ health that is presented by the emissions from the buses that transport them to and from school. This program encourages upgrades to newer buses, retrofitting of catalytic converters where appropriate, and other strategies to “clear the air” for these students. A key to this effort will be the inclusion of biodiesel in the fuel system for these buses. This presents the most sensible, economic, and beneficial means to reduce the pollutants in the exhaust stream of these buses and thus ensure better health for our schoolchildren.