Asphalt is a mixture containing thousands of different chemicals. The chemicals in asphalt vary depending on the source of the crude oil, the type of asphalt being made, and the process used. In general, the fumes are a mixture of several different types of chemicals including:
Many of these chemicals also are emitted by other combustion sources such as cars and trucks, fireplaces and wood stoves, wildfires, and industries. All of these chemicals are often found in outdoor air at low levels; however, elevated levels of these chemicals may be found near an operating asphalt plant.