After scientists linked the Austin PAH pollution to runoff from coal tar-based sealant applied to a parking lot, the city banned the sale of such coatings.

Municipalities in Wisconsin and Florida are considering similar bans and home improvement chains The Home Depot and Lowe’s have discontinued sale of coal tar-based sealants, Hogue said. Manufacturers of coal tar-based sealcoats dispute the link, and claimed most PAHs in Austin waterways originated from the city’s highways, which they said collect PAHs from motor vehicle exhaust, tire wear and oil drips.