Ban coal tar, high-PAH parking lot sealants

Steve Greason encourages residents to take action to improve water quality

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Editor’s note:This is one in a continuing series of guest opinions about fostering environmental stewardship and leadership. The series is coordinated by ACES, the Alliance of Climate and Environmental Stewards.

I’m writing about the Nov. 3 front-page article about ACES’s Merrimack River Survey written by Jim Sullivan of The Daily News. It’s good to see more attention is made concerning the condition of the river.

I’m a West Newbury resident and enjoy boating on the river. The water quality? Not so much. The brown slicks and smell of disinfectant coming from sewage treatment plants upriver is worse than all the “no wake” zones we boaters have to put up with.

Without a doubt, the biggest threat to the river are combined sewer overflows (CSOs), when heavy rains overwhelm treatment plants and they discharge untreated wastewater.

This has been well-publicized by the Merrimack River Watershed Council, who monitors the river after CSO events. Fixing this problem will take time and be a huge cost.

One pollutant, however, which is easier to fix, is to ban the use of coal tar sealcoating products used on driveways and parking lots. These products contain high concentrations of polycyclic aromatic hydrocarbons (PAHs), which are toxic to human health and the environment.

Coal tar is a byproduct of the coking process and has a strong creosote-like odor. If a parking lot stinks on a hot summer day, it’s coal tar you’re breathing.

Like PFAS, most people don’t know about this new emerging contaminant. Dust and fragments wash off the parking lot surface into storm water drains and wetlands and accumulate over time. PAH concentrations in coal tar sealants can exceed 100,000 ppm (mg/Kg).

I’m a scientist and expert in this field. My business, Sitelab Corp., worked with Chesapeake Bay Trust on a federal U.S. Environmental Protection Agency grant with the Department of Energy and Environment in Washington, D.C., to develop a laboratory protocol to test and certify driveway sealants.

Products with PAHs below 1,000 ppm qualify for gold certification. Products with PAHs below 10,000 ppm qualify for silver certification. Regulators around the country are starting to ban the use of coal tar and other high-PAH sealcoat products to help protect their watersheds.

Sitelab is working with Austin, Texas, and Charlotte, N.C., who enforce the 1,000 ppm limit and require manufacturers to have their products tested by a certified laboratory prior to use. See this list for examples:

A large number of cleaner, PAH-friendly products made with asphalt are available and contain no or very few PAHs. The bucket brands sold at retail stores are all asphalt-based.

These products are mostly used by homeowners on driveways and represent only a small percentage of the market and environmental impact. Most sealcoating is performed at the commercial level on parking lots, like shopping centers, schools and office buildings, where coal tar is most often used. Urban runoff is bound to carry these compounds into the Merrimack.

Maine recently passed a ban into law with a 10,000 ppm PAH limit, which is too high, but a good start. New York State and Canada also just passed bans and both have plans in the works to lower the limit to 1,000 ppm as a result of my outreach effort.

If our neighbors are doing it, we should, too. It’s time New Hampshire and Massachusetts take action. Ask your elected officials to get legislation started. It can only help the river.

This site is a good resource with map showing bans in US:

This column was coordinated by ACES youth corps member Ana Satir. She asks, if you care about issues like these and would like to learn more and possibly do a bit more or have any questions, please send an email to or sign up for ACES newsletter here:

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Steve Greason

Steve Greason has over 20 years experience working with ultraviolet fluorescence technology testing petroleum hydrocarbons. He is the owner of Sitelab Corporation which has been the industry leader in providing portable hydrocarbon field analyzers to the oil and gas, environmental and soil remediation markets.  Using his science and engineering expertise, Steve has provided advice on PAH to legislative and regulatory bodies in several states and Canadian provinces.

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