Exhaust from diesel-powered vehicles is composed of vapors, gases and fine particles (diesel exhaust contains 20-100 times more particles than gasoline exhaust). Federal agencies have classified some of these components as known human carcinogens and hazardous air pollutants under the Clean Air Act.

Exposure to diesel exhaust is a known cause of both asthma and lung cancer, and can exacerbate respiratory diseases through inflammation and irritation of the airways. Exposure to polycyclic aromatic hydrocarbons (key combustion by-products found in diesel exhaust) has been linked to an increased risk of breast cancer.

There is no known safe level of exposure to diesel exhaust. A recent study on children’s exposures to diesel exhaust from riding school buses suggests that regulations regarding idling and maintenance are urgently needed.

The case for replacing diesel with cleaner and renewable fuels should also be proposed to our decision makers. Biodiesel is one alternative fuel that has gone through rigorous testing for health and environmental effects. This fuel, made from vegetable oils (primarily soybean), can reduce targeted cancer-causing compounds by up to 90 percent. In addition, biodiesel works in diesel engines with little or no engine modifications.

A second alternative is low sulfur fuels. While conventional diesel can contain upwards of 700 ppm of sulfur, low sulfur fuels, often called ‘cleaner diesel’ or ‘green diesel’, contain no more than 30 parts per million (ppm) of sulfur. Low sulfur fuels produce fewer emissions of particulates, nitrogen oxides, volatile organic compounds (VOCs) and carbon dioxide. It is estimated that a complete conversion to low sulfur fuels would be the equivalent of removing two million vehicles from our roads.

National Biodiesel Board – The national trade association representing the biodiesel industry as the coordinating body for research and development in the US.

Diesel Exhaust in the United States – A report by the US Environmental Protection Agency (EPA) that documents the health and environmental effects of diesel exhaust.

Clean Air Council – Based in Philadelphia, the Clean Air Council is a member-supported, non-profit organization protecting the right to clean air via public education and community advocacy.


Children’s Exposure to Diesel Exhaust on School Buses by John Wargo, Ph.D., Environment and Human Health, Inc. (February 2002).