Facts About Diesel Exhaust

Diesel exhaust is a major source of air toxics. More than 40 substances are listed as hazardous pollutants. Because of their size, when these particles are inhaled, they can become trapped in the small airways of the lungs. These particles can be coated with potent mutagens and carcinogens.

Since 1990, diesel exhaust has been listed as a known carcinogen under California's Proposition 65, and in 1998, the California Air Resources Board (CARB) formally listed diesel particulate as a toxic air contaminant. The extensive scientific literature demonstrates that exposure to diesel exhaust increases the risk of developing lung cancer and other non-cancer health problems.

Numerous studies have found that fine particles impair lung function, aggravate respiratory illnesses such as asthma, bronchitis and emphysema, and are associated with premature deaths. Dozens of studies link airborne fine particle concentrations to increased hospital admissions for respiratory diseases, chronic obstructive lung disease, pneumonia and heart disease. In April 2003, the <%$alatitle%> released a report called Closing the Diesel Divide, Protecting Public Health From Diesel Air Pollution to spotlight the magnitude of the impact of diesel air pollution and to show policy makers and the public that there are life-saving solutions at hand.

Recent studies on the relationship between asthmatic responses and proximity to major roadways add to concerns about diesel's contribution to asthma. Studies have shown that the proximity of a child's school or home to major roads may be linked to asthma, and the severity of children's asthmatic symptoms increases with proximity to truck traffic. Studies are ongoing in this area of research.

In Washington, asthma is now an epidemic where one in ten adults and one in nine children has this chronic lung disease.

Protecting Yourself From Diesel is Nearly Impossible

Children are among those most vulnerable to the health risks of diesel exhaust exposure, yet they ride on some of the oldest and most polluting diesel buses on the road today, sometimes for hours at a time. Constant, significant exposure to diesel exhaust, coupled with a child's heightened vulnerability to pollution, is widely recognized as a potential cause of severe health problems in children. It is well known, for example, that children raised in heavily polluted areas face the prospect of reduced lung capacity and prematurely aged lungs. In addition, childhood asthma is on the rise and is, among chronic conditions, the leading cause of absenteeism from school.

Another vulnerable population is low-income communities where large numbers of people of color and the elderly live. These communities are often located near freeways, shipping yards, and other areas with heavy diesel truck traffic.

Diesel emissions are also released throughout the process of fuel production, refining, distribution and dispensing. Diesel refining, distribution and storage facilities are predominantly located in these communities, which are already burdened by major air pollution and toxic risks. Continued use of diesel fuel increases toxic air pollution and raises the risk of lung cancer and other lung diseases in these communities.

To totally avoid diesel exhaust exposure, Washingtonians would have to stay indoors with the windows and doors tightly sealed. There are ways to reduce the risk, such as limiting exercise and activity to areas far from freeways or industrial complexes. But for most Washingtonians, avoiding diesel exhaust is nearly impossible.

Reducing Fine Particles and Toxic Emissions

• The incidence and severity of asthma attacks, chronic bronchitis, emphysema, coughing, wheezing and phlegm formation.
• Lost school days for children and workdays 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.
• Hospital visits due to asthma and other respiratory ailments. Exposures to diesel exhaust have been linked to increased hospital admissions for respiratory and heart diseases and up to 60,000 premature deaths annually.
• Cancer risk from diesel exhaust, which is estimated to be as high as 1,400 in a million in southern California studies. The risk of cancer from diesel exhaust is not only for occupational levels of exposure. Breathing outdoor air, which contains diesel exhaust, also puts ordinary people at risk, especially school children. (For comparison, we spend millions of dollars every year on toxic waste cleanups to reduce risk to levels of one in a million.)
• Reduce chronic health effects on children's lungs. Fine particles and toxic emissions have been shown to reduce lung function 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.
• Susceptibility to allergens. Reactions to allergens such as pollen can be more severe when there is also exposure to diesel exhaust.
• Exposure to priority pollutants. The Environmental protection Agency 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 large amounts of particulates and one of the precursors of ozone.

Eliminating Diesel Exhaust Without Eliminating Buses and Trucks

To significantly reduce the amount of pollutants and cancer-causing toxic air contaminants, Washington must promote cleaner alternatives where possible and substantially reduce diesel emissions through the use of retrofit devices and lower-emitting diesel fuel. The <%$alawtitle%>^® is advocating for restrictions on diesel emissions and promotion of alternative fuels. We will also work with school districts to encourage them to switch over to buses powered by natural gas. Until we make a concerted effort to rid our state of dirty diesel fuel and transition to lower-emission fuels and cleaner alternative fuels, diesel exhaust will remain a serious public health threat.

We need to support regulations and voluntary efforts to curb emissions from school buses, as well as trucks and cars. One such voluntary program is the Puget Sound Clean Air Agency.s Diesel Solutions program, a partnership that encourages retrofits of diesel vehicles and the use of low sulfur diesel fuel in public and private diesel fleets. This voluntary initiative will leverage ultra-low sulfur diesel fuel into western Washington and enable a wide range of public and private fleets to join a consortium to retrofit diesel vehicles. To learn more go to the Diesel Solutions page on the Puget Sound Clean Air Agency website: Puget Sound Clean Air Agency - Diesel Solutions

Health Studies:

Fine particles and toxic emissions have been shown to reduce lung function 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.

• Multiple Air Toxics Exposure Study in the South Coast Air Basin: MATESII, Draft Final Report. South Coast Air Quality Management District, November 1999.
• Lung Cancer, Cardiopulmonary Mortality, and Long-term Exposure to Fine Particulate Air Pollution. Journal of the American Medical Association, 2002; 287:1132-1141.
• US Department of Health and Human Services, 9th Report on Carcinogens (PDF file). Revised January 2001.
• Proposed Identification of Diesel Exhaust as a Toxic Air Contaminant. Part B: Health Risk Assessment for Diesel Exhaust. California EPA, May 1998.
• Health Assessment Document for Diesel Exhaust. Office of Research and Development, US EPA/600/8-90/057E, July 2000.
• Air Quality Criteria for Particulate Matter on health effects associated with PM2.5. US EPA/EPA 600/P-99/002aB, bB, March 2001. <%doc>
• Children's Exposure to Diesel Exhaust on School Buses. Environment and Human Health, Inc., February 2002.

School Bus Studies:

• http://www.nrdc.org/air/transportation/schoolbus/sbusinx.asp

• http://www.ehhi.org/pubs/children_diesel.html

Seattle Air Toxicity Study 2001:

The Clean Air Agency's report is based on actual air monitoring conducted by the state Department of Ecology and on agency staff analysis of the sources of toxic air pollutants uncovered by the monitoring. The staff analysis includes review of monitoring data and NATA modeling, emission inventories, source apportionment and application of best available risk factors.

This is the first time a relatively large group of toxic air pollutants has been studied, analyzed for cumulative health effects and then ranked by their effect on people's health. The data indicate the cancer risk from outdoor air toxics could be as high as about 700 in a million.

• http://www.pscleanair.org/news/other_pubs.shtml#.20020516psatedf