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Health Effects of Diesel Emissions

Diesel exhaust contains several pollutants that contribute to the formation of ground level ozone, acid rain, and are harmful to public health alone or in combination with other substances.

Diesel emissions also increase pollutant levels including ozone and fine particles. Harmful ozone comes primarily from vehicle exhaust, gasoline vapors, and industrial emissions. Fine particles come from a variety of natural and industrial sources, including the sources of harmful ozone levels. Diesel emissions directly release fine particles into the air and on hot days, diesel exhaust from on-road vehicles and off- road equipment increases the level of ground ozone. These high levels of ozone and fine particles are detrimental to public health and the environment.

What are the effects?

The health effects of diesel exhaust are both acute, from short-term exposure, and chronic, from long-term or repeated exposure. Specific health risks and their severity depend upon the amount of chemical exposed to as well as the duration of the exposure. An acute exposure to diesel exhaust could cause an irritation of the eyes, nose, throat, and lungs as well as lightheadedness. Chronic exposure to diesel exhaust can have several more severe effects on human health. Chronic exposure is likely to occur when a person works in a field where diesel is used regularly or experiences repeated exposure to diesel fumes over a long period of time. Human health studies demonstrate a correlation between exposure to diesel exhaust and increased lung cancer rates in occupational settings. Experimental animal inhalation studies of chronic exposure to diesel exhaust have shown that a range of doses cause varying levels of inflammation and cellular changes in the lungs. Human and laboratory studies have also provided considerable evidence that diesel exhaust is a likely carcinogen.

Who is at risk?

Individuals may react differently to the same type of exposure. The more sensitive portion of the population is likely to have a stronger reaction than the average healthy person. Children, the elderly, and people with cardiovascular or lung disease, such as emphysema and asthma tend to be more vulnerable to exposure.

Diesel Exhaust Pollutants

Some of the pollutants found in diesel exhaust are listed below:

Carbon Dioxide

Carbon dioxide is formed as a by-product of fuel combustion and is toxic in higher concentrations.

Carbon Monoxide

Carbon monoxide is formed by incomplete fuel combustion. Carbon monoxide reduces the flow of oxygen in the bloodstream and is of particular concern to people with cardiovascular disease.

Fine Particulate Matter (PM 2.5)

PM 2.5 is a mixture of solid particles and liquid droplets in the air. Because of its small size, fine particulate matter can be deposited deep in the lungs where it can cause health problems. Recent studies have shown an association between particulate matter and premature mortality from respiratory and cardiovascular disease and increased incidence of respiratory illness particularly in children and the elderly. For adults with heart or lung conditions, exposure to fine particulate matter can cause more illness and in some cases premature death. More than 90 percent of the particulates found in diesel exhaust are fine particles.

Hazardous Air Pollutants

Diesel exhaust contains 40 substances that the U.S. Environmental Protection Agency (U.S. EPA) lists as hazardous air pollutants. Fifteen of these pollutants are considered probable or known human carcinogens.


Hydrocarbons are formed by incomplete fuel combustion. When combined with nitrogen oxides in the presence of sunlight, hydrocarbons produce ground-level ozone, which can irritate the eyes, damage lungs, and aggravate respiratory problems. Symptoms include coughing, shortness of breath, and decreased lung function. Many hydrocarbons are also considered hazardous air pollutants.

Nitrogen Oxides

Nitrogen oxides are by-products of fuel combustion and contribute to the formation of ground-level ozone. Health effects include coughing, shortness of breath, and decreased lung function.

Additional Resources

How can you minimize your risk?

If you have a diesel vehicle, avoid idling. Turn your engine off when you are stopped.

Keep your diesel vehicle well tuned and maintained.

When purchasing a diesel vehicle, purchase one that meets or exceeds U.S. EPA’s new emissions standards ahead of schedule.