healthy house institute

4 Free HHI Books:

Creating a Healthy Household, The Healthy House Answer Book, Healthy Home Building, The Healthy House 4th Edition
Your email will only be used as described in our Privacy Policy

Follow us on Twitter



Proud Supporter of:




Blog/Opinion: Live Near a Parking Lot? Cars May Not Be Your Only Concern

We might not think a lot about the dust in our homes until it causes an unsightly layer of gray fluff on our furniture or makes us sneeze. However, depending on where you live, the dust wafting into your house may be worse for you than you think. This is especially true if you live close to a parking lot sealed with coal-tar sealants (CTS). [Editor's Note: An excellent resource on this subject is]


blog continues below ↓

We do not strictly control Google ad content. If you believe any Google ad is inappropriate, please email us directly here.

Coal-tar sealants contain exceptionally high concentrations of polycyclic aromatic hydrocarbons (PAHs), which are a group of compounds that have similar structure. They are typically formed when organic materials such as coal and oil are not completely burned. They have been classified by the U.S. Environmental Protection Agency (EPA) as potential carcinogens.1


Possible Alternatives to Coal-Tar Based Sealcoats

In another study done in 2006 by the USGS, their report contained suggested safer alternatives to coal-tar based sealcoats. These alternatives included the use of concrete and unsealed asphalt, or an asphalt-based sealcoat that contains more than a thousand times less PAHs. The study showed a clear difference between one alternative and CTS. “Particles in runoff from coal-tar based sealcoated parking lots had concentrations of PAHs that are about 65 times higher than concentrations in particles washed off [unsealed asphalt] parking lots.” -

One of the few studies that have examined the potential health affects of PAHs from these materials in dust and soils is a recent study involving the U.S. Geological Survey (USGS) and Baylor University toxicologist, E. Spencer Williams. The authors calculated potential cancer risk in five scenarios. In the study, they used benzo[a]pyrene (B[a]P) equivalents since B[a]P is proposed to be the most potent carcinogen of the PAHs.1 They found that soil near asphalt sealed with CTS was the “primary driver of [cancer] risk” but that household dust found in homes near sealed parking lots was a close second.

How much risk? They found that the excess lifetime cancer risk (ELCR)* from soil and dust exceeds 1 x 10-4 “using deterministic and probabilistic methods”. Maximum exposure to household dust in early stages of development (0-6 years of age) could cause an “estimated ELCR of 6 x 10-5”. Considering the EPA’s view of these ELCRs, the risk factors merit remediation.


EPA Risk Characterization

“The level of total cancer risk that is of concern is a matter of personal, community, and regulatory judgment. In general, the U.S. EPA considers excess cancer risks that are below about 1 chance in 1,000,000 (1×10-6 or 1E-06) to be so small as to be negligible, and risks above 1E-04 to be sufficiently large that some sort of remediation is desirable. Excess cancer risks that range between 1E-06 and 1E-04 are generally considered to be acceptable (see Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions (Memorandum from D. R. Clay, OSWER 9355.0-30, April 1991), although this is evaluated on a case-by-case basis and EPA may determine that risks lower than 1E-04 are not sufficiently protective and warrant remedial action.” -EPA

Overall, this study raises a red flag over the safety of coal-tar sealants used near homes or schools. The excess lifetime cancer risk from PAHs found in soil and household dust near asphalt sealed with CTS is significant and deserves further attention.

You can read more about this study here:


Additional Resources:

Field Test for Coal Tar Sealant Determination


What if CTS is on My Driveway?


Additional References:
1Massachusetts Department of Environmental Protection


*The additional or extra risk of developing cancer due to exposure to a toxic substance incurred over the lifetime of an individual. -





HHI Error Correction Policy

HHI is committed to accuracy of content and correcting information that is incomplete or inaccurate. With our broad scope of coverage of healthful indoor environments, and desire to rapidly publish info to benefit the community, mistakes are inevitable. HHI has established an error correction policy to welcome corrections or enhancements to our information. Please help us improve the quality of our content by contacting with corrections or suggestions for improvement. Each contact will receive a respectful reply.

The Healthy House Institute (HHI), a for-profit educational LLC, provides the information on as a free service to the public. The intent is to disseminate accurate, verified and science-based information on creating healthy home environments.


While an effort is made to ensure the quality of the content and credibility of sources listed on this site, HHI provides no warranty - expressed or implied - and assumes no legal liability for the accuracy, completeness, or usefulness of any information, product or process disclosed on or in conjunction with the site. The views and opinions of the authors or originators expressed herein do not necessarily state or reflect those of HHI: its principals, executives, Board members, advisors or affiliates.

(Note: The views expressed in this blog post are those of the author, and do not necessarily represent those of The Healthy House Institute, LLC.)

Live Near a Parking Lot? Cars May Not Be Your Only Concern:  Created on January 31st, 2013.  Last Modified on February 5th, 2013

About Allison Rathey Kirby

Allison Rathey Kirby is Healthy House Institute's (HHI’s) Associate Editor and Director of Social Media. Formerly HHI's Tool Listing Editor, Allison has been with HHI for seven years - managing, editing, and contributing "healthy" content to the site. Allison is also the Associate Editor for HHI's sister site, The Housekeeping Channel.


We do not strictly control Google ad content. If you believe any Google ad is inappropriate, please email us directly here.



Information provided by The Healthy House Institute is designed to support, not to replace the relationship between patient/physician or other qualified healthcare provider.

Education Partners



Popular Topics: Air Cleaners & Air Purifiers | Allergies & Asthma | Energy Efficiency & Energy Savings | Healthy Homes | Green Building
Green Cleaning | Green Homes | Green Living | Green Remodeling | Indoor Air Quality | Water Filters | Water Quality

© 2006-2018 The Healthy House Institute, LLC.


About The Healthy House Institute | Contact HHI | HHI News & Media | Linking Resources | Advertising Info | Privacy Policy | Legal Disclaimer


HHI Info