Coal tar - Coal tar is a byproduct of the coking of coal when coal is carbonized to make coke. It is a brown or black liquid of extremely high viscosity which smells of naphthalene and aromatic hydrocarbons. Coal tars are complex and variable mixtures of phenols, polycyclic aromatic hydrocarbons (PAHs) and heterocyclic compounds.
Coal tar pavement sealant - Coal tar sealants are surface finishes for parking lots, driveways, and airports used both commercially and by homeowners across the country. They are usually not applied to public streets. They contain varying concentrations of coal tar depending on product and formulation. They are the black, shiny emulsion painted or sprayed on asphalt pavement in an effort to protect and beautify the asphalt. Coal tar pavement sealant is marketed as a way to extend the life of asphalt, while also restoring a rich dark color. It is also marketed as having better resistance to gasoline, motor oil, and kerosene is allegedly more durable and absorbs less water while retaining its color longer.
Polycyclic Aromatic Hydrocarbons (PAH’s) - PAH’s are a group of chemicals formed during the incomplete burning of coal, gasoline, wood, garbage or other organic substances such as tobacco, charcoal broiled meat, and incense. As a pollutant, they are of concern because some compounds have been identified as cancer-causing. For example, one PAH compound, benzo[a]pyrene, is notable for being one of the first chemical carcinogens discovered; one of many found in cigarette smoke. PAHs are lipophilic (mix more easily with oil than water). The larger compounds are less water-soluble and less volatile (less prone to evaporate). Therefore, PAHs in the environment are found primarily in soil, sediment and oil substances, as opposed to water or air. However, they can be found in particulate matter suspended in air.