Diesel Emissions Reduction
Olympic Region Clean Air Agency (ORCAA) and other local air quality agencies received funding through the Department of Ecology to assist school districts in reducing emissions from diesel-powered school bus fleets around the state. Through this Clean School Bus program, ORCAA has retrofit most of the school buses within its six-county jurisdiction with Diesel Oxidation Catalysts (DOCs). These DOCs, attached to the bus exhaust system, reduce fine particle emissions by 30 percent and toxic emissions by up to 50 percent. Additional retrofits are currently underway to help further reduce air toxics from the bus operations.
Why is this important? School buses remain the most means of transportation of children to and from school, and the safest. Yet the very buses that provide such safe transport also pose health threats to those children. Diesel pollution has serious health implications for everyone, especially children. Reducing bus emissions, therefore, serves the community at large, but more important, it provides additional health protections for our kids.
Since 2003, Washington state’s schoolchildren have been the beneficiaries of one of the largest statewide, state-funded, voluntary school bus retrofit program in the country. It provides enough funding over five years to retrofit three-quarters – 7,500 of 9,000 – of the state’s school buses.
The state Legislature set aside funds specifically for this program. In 2003, the Legislature passed, and the governor signed, ESSB 6072 . This legislation provided approximately $5 million per year for five years for the statewide program of school bus retrofits. Nearly 9,000 buses statewide will be cleaned up thanks to this program.
The Problem with Diesel; It's all About the Exhaust
Diesel exhaust is one of the top sources of air pollution in our jurisdiction. Only smoke from outdoor burning matches the level of pollution that comes from diesel engines. Sources of diesel emissions include diesel trucks, buses and cars (these are all referred to as “on-road sources”); diesel-powered marine vessels, construction equipment, logging and farm equipment, and diesel locomotives (“non-road sources”).
Diesel exhaust comprises a toxic cocktail of pollutants, one of the primary sources of concern for human healt is fine particulate matter (PM2.5 — or particulate matter smaller than 2.5 microns in diameter). Some studies estimate that 78 percent of the potential cancer risk from exposure to outdoor air toxics is directly attributable to PM2.5. Other health problems linked to PM2.5 include heart disease, asthma, chronic bronchitis and lung disorders.