In 1988, the International Association for Cancer Research (IARC) classified diesel exhaust as a "probable carcinogen to humans." In 2012, it stopped hedging its bets and dropped the "probable."

A large study by the National Cancer Institute (NCI) and the National Institute for Occupational Safety and Health found an increase in the risk of death from lung cancer among underground miners exposed to diesel fumes. The research also found a positive association with an increased risk of bladder cancer.

Diesel Exhaust

We use diesel to power trucks, buses, agricultural equipment, and backup generators. It's more versatile and less expensive than gasoline and other power sources. Diesel combustion produces thousands of gases and fine particles, and at higher concentrations than gasoline combustion. At least 40 of these particulates are toxic and include benzene, arsenic, formaldehyde, and nitrogen oxides, which are all cancer-causing suspects. These particles are less than one-fifth the thickness of human hair and small enough to penetrate deep into lung tissue. They may contribute to cell mutations that lead to cancer.

The Diesel Exhaust in Miners Study also evaluated the risk of death associated with diesel exhaust exposure and observed an increased risk for lung cancer death with increasing levels of exposure. The risk among the most heavily exposed workers was about three times greater than the risk for workers with low exposure.

Certain occupations, such as mining or operating diesel powered trucks or machinery, expose workers to high rates of diesel fuel. However, we are all exposed to some level of diesel exhaust, especially if we live or work in urban and industrial areas.

According to the NCI, more than a quarter million people in the U.S. will be diagnosed with lung cancer in 2012 and more than 160,000 will die from it.

What Are We Doing?

The Mine Safety and Health Administration and the Occupational Safety and Health Administration, which oversees all other work environments, are establishing workplace standards to limit diesel exhaust exposure. The Environmental Protection Agency (EPA) is developing policies to reduce the public's exposure to diesel pollution.

State and local agencies are also establishing diesel exhaust guidelines. The California Air Resources Board, for example, implemented a Diesel Risk Reduction Plan, which includes requirements for cleaner burning diesel fuels, retrofitting older diesel engines with particle-trapping filters, and using alternative fuels such as natural gas, propane, and electricity.

If you want to limit your personal exposure to diesel exhaust, the EPA's website offers numerous tips to get you started.


California Office of Environmental Health Hazard Assessment. "Health Effects of Diesel Exhaust." Web. 2007.

National Cancer Institute. "Diesel Exhaust in Miners Study: Questions & Answers." Web. 2 March 2012.

United Nations. "UN health agency re-classifies diesel engine exhaust as 'carcinogenic to humans'." UN News Center. Web. 12 June 2012.

Mine Safety and Health Administration. "Practical Ways to Reduce Exposure to Diesel Exhaust in Mining --A Toolbox." Web.

Environmental Protection Agency. "What You Can Do." Web. 6 June 2012.

World Health Organization. "Diesel exhaust carcinogenic." Bulletin of the World Health Organization 90 (7) (2012): 477-556. Web.