The Threat of Coal-Tar Driveway and Parking Lot Sealants

photo of Brian Will

Brian Will

Rachel Carson in her seminal book “Silent Spring” raised public consciousness to the threat of commonly used chemicals such as DDT.  Since the 1962 publication of Carson’s book, society has become aware of many other products that threaten human health and the environment, including cigarettes, refrigerants, neonicotinoids, and asbestos. In the last twenty years, one chemical product that is alarming environmentalists is toxic coal-tar driveway and parking lot sealants, widely used in residential neighborhoods and strip mall parking lots in the Midwest.

Coal-tar sealants are primarily composed of coal-tar pitch, which has 1,000 times more carcinogenic polycyclic aromatic hydrocarbons (PAHs) than an equally effective alternative product, asphalt-based sealants.  Asphalt-based sealants are widely available and similarly priced to coal-tar sealants and are a considerably less toxic.

Coal- tar sealant is a black, acrid-smelling goo that is spread on homeowner driveways and parking lots on warm days.  If you have ever walked near a newly sealed driveway and noticed the strong odor of mothballs, you probably were inhaling PAHs from the coal-tar fumes.  As coal-tar sealant is being poured and for years afterward, the carcinogenic PAHs present in the coal-tar gradually spread into the environment in the form of dust. Tires, snow shovels, leaf blowers, brooms, shoes, and bare feet can spread the poisonous dust into the environment as well as bring it inside homes.

The National Cancer Institute has classified coal-tar sealant as a Class 1 carcinogen, and the United States Geological Survey (USGS) has determined that the PAH’s from coal-tar sealed driveway and parking lot runoff cause birth defects and death in fish, amphibians, and invertebrates.   Coal-tar sealants are so toxic that most nationwide home improvement retailers like Lowe’s, Ace, Home Depot, and TruValue no long sell them.  Thanks to education and advocacy by watershed organizations, many states have implemented bans or restrictions on the selling and application of coal-tar, including Minnesota, Washington, New York, Maryland, California, and Maine. Milwaukee, Washington, D.C., Ann Arbor, Austin, San Antonio, multiple suburbs of Chicago, and over hundred other cities and towns have banned coal-tar sealants.

Since coal-tar sealants are not usually available in retail stores, residents run the risk of being exposed to coal-tar when they hire contractors to seal their driveways. Residents can protect themselves and the environment by informing the contractor that they do not want coal-tar products, and ask for a copy of the Material Safety Data Sheet (MS-DS) of the product they intend to use. If the Chemical Abstract Number (CAS) for the product is 65996-93-2, then that contractor intends to use a coal-tar sealant.

You can learn more about the dangers of coal-tar sealants by visiting the USGS website.  There are also multiple helpful videos on YouTube.

Brian Will

Support FLOW through our Milkweed Mania fundraiser!

In collaboration with Riverside Native Perennials, FLOW is hosting a milkweed sale. Milkweed is great for pollinators, and the butterflies will love you for it! We would love to see more of these native plants within the Lower Olentangy Watershed. The price is $12 per pot, containing 2-3 stems of milkweed. There are a variety of species available including Sullivant’s (Prairie), Whorled, Butterfly, Swamp, and Common.

Ready to order? Visit to order online. All orders must be picked up on Sunday, September 12th from 12PM-3PM at Sawmill Wetlands Education Area (2650 Sawmill Pl. Blvd., Columbus, OH 43235). Mark your calendars! Any orders not picked up during that time frame will be donated to a local greenspace area.

Please email us with any questions!

Thank you for supporting FLOW and our Greenspace Implementation Plan!

The Dangers of Toxic Coal-Tar Driveway and Parking Lots Sealants to the Watershed

photo of Brian Will

Brian Will

Come Join FLOW as we return to our Outreach and Education Speaker Series on Tues., Sep. 14, 5:30-6:30 at Whetstone Library!  

Brian Will is an organizer of Sustainable Grandview, a grassroots, community-based citizens alliance in Grandview Heights dedicated to pursuing a cleaner and more environmentally friendly city.  He has been on the board of trustees of the Solid Waste Authority of Central Ohio (SWACO) since 2016 where he leads the Solid Waste Plan committee.  He is employed at the Ohio State Wexner Medical Center where he works in medical education and is a leader on the med center’s green team.



a freshly sealed driveway

As coal tar sealants degrade, their toxic particles are washed into the waterways and are tracked into our homes.

From a sustainability perspective, Brian’s primary interest is advocating for the protection of wildlife and natural habitat, especially native trees and plants, waterways and prairies.  To this end, he volunteers with Friends of Lower Olentangy Watershed, the Grange Audubon Center, Green Columbus, Citizens Climate Lobby, and the Sycamore Land Trust.

Brian has achieved household carbon neutrality with the help of rooftop solar panels, reducing household energy usage, diet and lifestyle changes and purchasing carbon offsets through Carbon Neutral Ohio.

In his role with Sustainable Grandview, Brian has written white papers and made presentations to the city council and mayor on various environmental topics, including the importance of tree canopies and the dangers of coal-tar driveway and parking lot sealants.  Brian will be discussing the latter, as toxic coal-tar represents a significant threat to humans as well as aquatic life in the watershed

Cleaning up Your Household’s ‘Carbon Trash’ and Becoming Carbon Neutral

OSU Wexner Medical Center’s Green Team Monthly Webinar Series presents:

Clean up Your Household’s ‘Carbon Trash’ and Become Carbon Neutral – with Daniel Poynter. 

Tuesday, Jul 20, 2021 12:00 PM Eastern Time (US and Canada)

About the speaker:

Daniel Poynter  founder @Carbon Neutral Ohio, one state chapter of a national grassroots movement
Daniel Poynter founded Carbon Neutral Indiana (CNI) in April 2020, and his non-profit organization is now expanding to other states, including Ohio ( CNI helps households measure and clean up their carbon footprints. Along the way, they’ve demonstrated a self-financing, scalable social movement that can be expanded across other states. Before founding CNI, Daniel was a software engineer, professional advisor to 100+ social entrepreneurs, MacArthur Foundation Young Innovator, and speaker at 20 international academic institutions.

Be a FLOW citizen scientist!

You can be a FLOW citizen scientist with just your smart phone and an iNaturalist account!

iNaturalist observations allow anyone to identify and share their observations of living things – animals, plants, fungi, and more.

We have added the Lower Olentangy Watershed as a “place” in iNaturalist, so any of your observations with coordinates within the watershed will automatically appear under that listing, helping us better determine the diversity of species in the watershed. It doesn’t have to be an unusual or rare species to be of interest.

You can search for Lower Olentangy Watershed or even Olentangy and see what wonders your watershed holds!

Upload your nature photo(s) to your iNaturalist account (it’s free!) and the site will offer suggestions to help you identify what you are looking at, and other users actively reach out and help confirm many of your identifications. The more detailed the photo the better, and you can add multiple photos of the same plant or animal.

Wildlife Habitat Creation for a Healthier Watershed

This is a section of a five-part series produced by FLOW to educate residents about backyard conservation.  

In the past thirty years, there has been a 90% increase in urban development in Ohio. This pattern is continuing – in the next thirty years, the Olentangy Watershed is expected to gain over 200,000 people. This rapid pace at which urban areas are growing is stressing environments and wildlife. One in four birds have been lost since 1970, Colony Collapse Disorder is taking down beehives at alarming rates, and the monarch butterfly is a candidate under the Endangered Species Act. Although the situation can look bleak, backyards and urban greenspaces act as oases to support wildlife. Cities and other urban areas can still support threatened species and migratory birds. Your very own backyard, however small, can make a big difference for wildlife. 

Not only does providing for wildlife bring joy and entertainment, it also strengthens local food webs and ecosystems. Wildlife needs four essential elements that you can provide in your very own landscape: water, food, shelter, and a place to raise young. 

Trees, shrubbery, and other plantlife are the backbone of a successful habitat. A good first step towards a thriving backyard is to remove exotic invasive plants and replace them with native species. Natives are adapted to the local environment, so generally require less maintenance and are heartier. Non-natives often do not provide good habitat or nutrition for local animals. For more information on plants indigenous to your area, consult a local nursery or this online list. Plantlife can provide food, shelter, and a place to raise young; so choosing and maintaining your plants is crucial. Try to cultivate a continuous season by choosing a variety of plants that bloom and bear fruit at different times throughout the year. Even dead plants and trees provide immense value. Dead logs or standing dead trees called “snags” can support more than 400 species. The cavities of dead plant stems provide habitat for nesting bee species. Take a look in your own backyard to see what plantlife already exists and how it might be enhanced. 

Four different types of bird feeders.

Photo by Tom Green/Creative Commons

Although natural sources of food, water, and cover can be successful on their own, supplemental feeders, shelters, and baths prove to be effective at attracting and supporting wildlife. Seeds and nuts are an important food source that you can provide for songbirds. A diversity of food and feeders helps to support birdlife. Sunflower seeds and suet are particularly popular, but for more information about feed choices, visit Elevated feeders, bird tables, and ground feeders all provide for different types of birds and should be placed near shrubs and trees. Birdhouses and boxes also encourage wildlife to nest in your yard. Different birds have different preferences about the size of the box and its entrance, its height, and which direction it faces. To determine what box will attract which birds, you can consult the US Fish and Wildlife Service’s online materials. Finally, choosing to install a birdbath or other water feature will also bring wildlife to your yard. When choosing a birdbath, choose shallow ones with rough textures or add rocks or pebbles to your bath. 

Small backyard pollinator gaHummingbirds, bees, bats, and butterflies each bring their own exceptional type of beauty and all play an important role as pollinators. To protect and provide for these species, you can plant a pollinator garden specifically suited to them. Pollinator gardens do best in sunny locations to support nectar-providing plants which should be grouped in clumps. Hummingbirds specifically like red and yellow tubular plants. Milkweed is critical to supporting some butterfly species. Try to avoid planting hybrids because they have often lost their pollen, nectar, and fragrance. Also avoid using insecticides near or in your pollinator garden. For more details on planting a pollinator garden, check out the US Forest Service’s online instructions.

Large bee hotel Supplemental feeders and shelters can help out pollinators, too. Hummingbird feeders can be filled with a solution of one part sugar to four parts water. Try to wash the feeders with soap and water every three to four days. Bees and butterflies like salt licks which can be made by mixing sea salt into puddles or mud in your yard. Solitary bees with no hives to protect (and thus no reason to sting) nest in narrow tubes. You can make bee homes or even “bee hotels” for these bees by drilling 1/8-inch to 5/16-inch holes in diameter a few inches deep in scrap lumber. For more information, check out this source. Bat boxes are another way to provide shelter for pollinators; you can learn about them here

When we attract birds and butterflies, we also attract other types of unwanted wildlife such as mammals. To avoid conflict with animals, secure garbage cans, avoid leaving out food, and check your house for places that would allow access to rodents. Be aware that these species can carry disease and should not be handled. Consult a pest or wildlife management company for more information or assistance. 

We all have backyards, whether they are acres or a few flower pots, and we can all make a difference for our wildlife. For more information on creating wildlife habitat and backyard conservation, you can consult FLOW’s website, the Ohio Division of Wildlife, or Ohio State University’s online resources. There is magic in your backyard, you just have to look for it.