Polycyclic aromatic hydrocarbons (PAHs) are a group of chemicals found in coal, crude oil, and gasoline, and are produced when coal, oil, gas, wood, refuse, and tobacco are burned. An example of a PAH is naphthalene, which is used to make mothballs and other chemicals. PAHs can bind to, or form, small particles in the air.

People are exposed to PAHs by breathing contaminated air or eating food on which PAH-contaminated air has settled. There can also be PAHs found in grilled or charred food.

The health effects from exposure to low levels of PAHs are unknown. Large amounts of naphthalene in air can irritate eyes and breathing passages. Workers who have been exposed to large amounts of naphthalene from skin contact with the liquid form, and from breathing naphthalene vapor have developed blood and liver abnormalities. Several other PAHs and some specific mixtures of PAHs are considered to be carcinogenic (cancer-causing) chemicals. EPA regulates the amount of some PAHs in drinking water and helps educate the public on reducing exposure to PAHs.

To learn more about PAHs and how to manage your risk to PAH exposure, see the resources below.