Maintaining Your Driveway Could be Hazardous to Your Health

Our roads, parking lots and driveways have taken a beating this winter and one of the signs (and smells) or spring is the seal coat which is used to protect the asphalt surfaces.  

Seal Coating is typically performed in the fall of spring given the fact driveway sealer is contains about 70% water by volume. Temperature and humidity work in tandem when it comes to drying and curing. High temperature and low humidity accelerate water evaporation; low temperature and high humidity take significantly longer to cure. The differences are staggering: a 20°F drop in temperature will double drying time while a 35°F drop will triple drying time.

While seal coatings contain a lot of water, coal tar-based sealcoat contains a lot of chemicals such as coal tar pitch which is known to cause cancer in humans and polycyclic aromatic hydrocarbons (PAHs) which are probable human carcinogens. 

PAHs also harm the aquatic food chain when the chemicals are washed into the watershed through stormwater runoff.  Studies have shown that PAHs are released from coal tar-based sealcoats into the air and homes, workplaces, and shopping centers, and also into ponds, lakes and streams.

Friction from vehicle tires grinds pavement sealcoat into small particles this dust is transported by wind, rain, and snowplows to nearby soil, and some is tracked into homes, where it becomes part of the house dust.  This dust is consumed incidentally when we put our hands or objects into our mouths.

For someone who spends their entire lifetime living adjacent to coal-tar-seal coated pavement, the average excess lifetime cancer risk is estimated to be 38 times higher than the urban background exposure. 

A team of Clemson University students performed tests on fish in urban Greenville and Easley streams and compared them to fish in non-urban Upstate streams. They found a much higher concentration of PAH toxins in the urban fish.  These toxins can cause tumors in some fish and may also cause heart defects.

Effective January 1, 2014 Minnesota has banned the use of coal tar-based sealcoats and even if your state does not have a ban in place, as a responsible citizen, be sure to specify coal tar-free products for your asphalt surfaces.  

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