Polycyclic aromatic hydrocarbons (PAHs)

We work with the Washington State Department of Health, along with industry and environmental stakeholders, to identify and take action to phase out the use of PAHs in Washington.

PAHs are known to cause cancer and other health issues, as well as environmental impacts. Working with partners, we have developed a chemical action plan to reduce or eliminate the use of these chemicals.

What are PAHs?

They are a group of more than 100 different chemicals and generally occur as complex mixtures. They can come from natural sources or from human activity.

What are the health and environmental impacts of PAHs?

Studies show that PAHs can cause:

  • Cancer.
  • Reproductive problems.
  • Weakened immune systems.

How are people exposed to PAHs?

PAHs are formed during the incomplete burning of organic matter such as coal, oil, gasoline, diesel, wood, and garbage.

The highest rates of exposure to people come from:

  • Charred or barbecued food.
  • Smoking cigarettes and secondhand smoke.
  • Burning wood in wood stoves and fireplaces.

Other products that release PAHs to the environment include:

  • Creosote-treated wood.
  • Vehicles (emissions, tire wear, improper motor oil disposal, and leaks).
  • Sealants used on asphalt (e.g., coal tar sealants).

How are we addressing PAHs in Washington?

Our agency, along with the Washington State Department of Health, have programs in place to reduce PAHs released from wood smoke, diesel, and creosote. Many organizations and local, state, and federal agencies also work to reduce emissions from combustion, and clean up contaminated soils and treated wood structures.

2012Chemical action plan for PAHs is finalized with specific recommendations to address the main sources of PAHs. Below, we go into detail on how we are addressing PAHs from wood smoke, vehicles, creosote-treated wood, smoking, food, and the impacts on stormwater:


Case study: Coal tar-based sealants

These are black liquids sprayed or painted on asphalt parking lots and driveways to enhance the surface. Studies, such as that of the United States Geological Survey, resulted in finding coal tar-based sealants to be a potential source of PAHs, and further evidence of the toxicity and health impacts of PAHs.

Photo credit: Justin McInnis, USGS. Public domain.