Why worry about diesel exhaust?

Diesel exhaust is a significant source of fine particle pollution, as well as a combination of more than 40 substances that are listed as hazardous pollutants. Because of their microscopic size, these fine particles can become trapped in the small airways of the lungs when they are inhaled.

Sources of diesel emissions include diesel-powered trucks, buses and cars (on-road sources); diesel-powered marine vessels, construction equipment, trains and aircraft support equipment (non-road sources).

Particulate matter from diesel exhaust overwhelmingly presents the highest health risk in the Puget Sound area, making up an estimated 78 percent of the potential cancer risk from exposure to outdoor air toxics.¹  Diesel particulate matter is also linked with health effects including heart problems, aggravated asthma, chronic bronchitis and premature death.

Additionally, diesel fuel combustion produces smog-causing oxides of nitrogen. Smog causes breathing difficulties, eye irritation and reduced resistance to lung infections and colds.  It is especially harmful to young children, the elderly and those with existing respiratory problems. And it mars our lovely mountain views.

Reducing fine particles and toxic emissions:

• Reduces the incidence and severity of asthma attacks, chronic bronchitis, coughing, wheezing and phlegm formation.

• Reduces lost school days for children and work days for parents and adult asthmatics.  A recent study by the Washington State Department of Health indicated that one in six households have someone who suffers from asthma.

• Reduces hospital visits due to asthma and other respiratory ailments.  Exposures to fine particles have been linked to increased hospital admissions for respiratory and heart diseases and up to 60,000 premature deaths annually.

• Reduces the health impacts on children from school buses. 

• Reduces chronic health effects on children's lungs.  Fine particles and toxic emissions have been shown to reduce lung function and growth in the developing lungs of children.  Children with decreased lung function may be more susceptible to respiratory disease and more likely to have chronic respiratory problems as adults.

• Reduces susceptibility to allergens.  Reactions to allergens such as pollen can be more severe when there is also exposure to diesel exhaust.

• Reduces cancer risk.  EPA, the World Health Organization, the Department of Health and Human Services, and the National Institute of Environmental Health Sciences have listed diesel exhaust as a likely carcinogen.   Recent studies indicate lung cancer risk can be significantly increased by exposure to diesel exhaust. A 100-cities epidemiological study indicates an 87 percent increase in lung cancer rates for each 10 micrograms increase in fine particle (PM2.5) levels.

• Reduces exposure to priority pollutants. EPA has established maximum concentrations for six priority pollutants, above which adverse health effects may occur.   The Puget Sound area is close to exceeding limits for particulate matter and ozone.  Diesel exhaust generates significant amounts of particulate matter and is one of the ingredients in the formation of ozone.