Waste 2 Resources > PBT Initiative > Polycyclic Aromatic Hydrocarbons (PAHs)

What are Polycyclic Aromatic Hydrocarbons (PAHs)?

PAHs are a group of more than 100 different chemicals and generally occur as complex mixtures. Studies have linked PAHs to cancer, reproductive problems and weakened immune systems. They are found in some natural substances like oil and coal and are formed during the incomplete burning of organic matter such as coal, oil, gas, wood, garbage, or other organic substances, such as tobacco and meat. Some PAHs are used to make products ranging from roofing tar to medicines, from plastics to pesticides.

PAHs were selected for the next CAP in the 2007 Multiyear CAP Schedule. PAHs came out high in most of the criteria ranking. They are toxic to organisms and are widespread in Washington’s environment. PAHs are also toxic to humans and are found in people. PAHs are released during commonplace activities, such as burning wood and driving cars, and from commonplace objects, like railroad ties. While some of these are regulated, opportunities for further intervention are still substantial.

Our initial look at sources in Washington found that wood burning stoves and fireplaces are the largest source of PAHs. Other major sources include creosote treated wood, vehicles, leaks and improper disposal of motor oil, and small engines such as lawn and garden equipment. For individuals, smoking and food are also important sources.

Advisory Committee

Ecology has convened an advisory committee to complete a CAP for PAHs that addresses all uses and releases of PAHs in the entire state and recommends actions to protect human health and the environment. Ecology is coordinating the CAP effort with other related efforts to address PAHs, including:

• PAHs are among many chemicals being studied as part of Ecology's Control of Toxic Chemicals in Puget Sound project. PAHs were one of the four chemicals that were rated as having the highest priority for early actions. This work will help the Puget Sound Partnership develop and implement a toxics reduction strategy that motivates the public to focus their efforts on addressing the most important sources of toxic chemicals.
• Ecology is also working with the Puget Sound Clean Air Agency on an area of Tacoma and Pierce County that is out of attainment with a federal clean air standard for fine particulate. PAHs are present in the fine particulate and both types of pollution come from many of the same combustion sources, such as wood burning stoves and diesel engines.

Coal Tar Sealants

Coal tar and asphalt-based sealants are black liquids that are sprayed or painted on asphalt parking lots and driveways. Published studies have identified coal tar sealant as a potentially important source of PAHs. RCW 70.295, passed in 2011, prohibits the sale and application of coal tar pavement sealants in Washington State. A retailer may not sell coal tar pavement products after January 1, 2012, and no person may apply a coal tar pavement product on a driveway or parking area after July 1, 2013.