Are you planning to sealcoat your driveway this summer? To reduce possible exposure to harmful chemicals during the process, consider using an asphalt-based sealcoat versus a coal-tar-based sealcoat. “Coal-tar-based sealcoat is a black liquid sprayed on driveways, parking lots, and playgrounds to produce a deep black finish,” explains John McManus with the Clermont County Storm Water Management Office. “However, this process contains high levels of chemicals called polycyclic aromatic hydrocarbons (PAHs) that may harm fish and can pose a risk of cancer to humans.”
Researchers at the University of New Hampshire Storm Water Center found that coal-tar-based sealcoats typically have about 1,000 times more PAH’s compared to an asphalt-based sealcoat.
The study results showed the parking lot covered with coal-tar-based sealcoat had 30 times more PAH’s than water running off an unsealed parking lot. The study also found that soil near the treated parking lot had highly elevated levels of PAH’s for up to three years after the sealcoat was applied.
In response to research demonstrating high levels of PAH’s in streams and soil, and the known risks to humans and the environment, several municipalities in the U.S, including Austin, Texas and Washington, D.C., have banned coal-tar-based sealcoat. Home improvement stores, including Home Depot and Lowes, along with several commercial seal coaters, have stopped selling and using these products. “Homeowners can choose not to sealcoat their driveways and lots, or, can choose a product that is asphalt-based,” said McManus. “These choices directly impact the health of your community and your environment.”