Coal-tar-based sealcoat — the black, shiny substance sprayed or painted on many parking lots, driveways, and playgrounds — has been linked to elevated concentrations of the contaminants polycyclic aromatic hydrocarbons (PAHs) in house dust. Apartments with adjacent parking lots treated with the coal-tar based sealcoat contained house dust with much higher concentrations of PAHs than apartments next to other types of parking lots according to new research.