Congressman Doggett: New EPA Coal Tar Study Supports Further Action

Congressman Lloyd Doggett (TX) revealed on Wednesday that the results of a new EPA study of coal tar pavement sealants support the need "to protect our waterways and especially our children."  The comment was made in a local Austin, Texas paper, the Oak Hill Gazette.  The Gazette also broke the story about Congressman Doggett's correspondence with the EPA about coal tar sealant pollution back in 2009.  The EPA's response to the earlier letter brought about the new study.

"I continue to work on legislation to phase out these sealants nationwide," said the Congressman.  In May, he sent a letter to the Administrator of the EPA, Lisa Jackson, complimenting the Agency's efforts to date on this topic, but challenged them to complete what was promised.  A summary of this letter can be found here.

The Congressman has been a lone, enduring congressional champion of this nationwide problem for many years.  Thank you Congressman Doggett!

Chicago Suburb Steers Away From Coal Tar Sealant Use

The Village of Hoffman Estates, Illinois recently opened bids for transportation projects and announced that coal tar sealants would not be used on the 2011 Crack Sealing and Seal Coating Project: 

As a part of ongoing environmental reviews and recent industry concerns, the Village chose to steer away from the traditional coal tar based seal coating products used in the past in favor of an asphalt emulsion sealer.

The contractor awarded the bid was within the engineer's construction cost estimate.  Contrary to what some have stated, budgets were preserved and no negative impact to business took place in the use of an alternative sealant product.

Are Hot Tar Cities Increasing Our Energy Bills While Decreasing Our Air Quality?

Research from the Lawrence Berkeley National Laboratory (LBL) indicates that they definitely are.  In partnership with the EPA, LBL has studied the ability of urban materials to reflect light and absorb heat.  The above graphic is of Washington, D.C. and the hot colors indicate the heated locations.  Some of this research was co-authored by the current Secretary of Energy Steven Chu before taking his current post.

In general the phenomenom is referred to as the "urban heat island."  Interestingly, as asphalt ages and goes from black to gray, the ability of pavement to heat up decreases, as seen in the graph below.  That's just about the time when a new application of coal tar sealants is applied to return it to a heat absorbing, deep black color.

  

Just how different is coal tar sealant from others in its ability to heat up a city?  Some research in Austin by a PhD student (Mohan Rao) at Texas State University looked at the reflectivity of coal tar and asphalt-based sealants, but it did not cover the full spectrum of light that can produce heat as shown in the graph below.  The reflectivity is affected by a material's properties in both the visible and invisible spectrums.  I have noticed some asphalt-based sealants are as much as 10 to 15 degrees F cooler than coal tar, but that is expected to vary from product type (asphalt, coal tar, acrylic, or gilsonite) and with the numerous amounts of filler used to blacken a sealant.

So how significant is this heating?  Dr. Chu states that appropriate cooling of urban impervious surfaces, roofs and pavement, would be the equivalent of removing the carbon emissions of all of the cars in the world for 11 years!  In Austin, Texas just reducing the sealant color from "new asphalt black" to aged gray, there is a measurable reduction in energy consumption by the 500,000 households there. 

The cost of hotter cities is not just in the electric bill either.  It also increases the production of lung-damaging ozone, which in turn can cost not only health care and productivity costs, but also compliance costs and jobs.

As you can see below the pavement percentage of a city is different across the US, but it is about double the surface area of rooftops.  With the frequency of sealant application much more often than roof replacement, doesn't it make sense to know which non-toxic products reduce our urban pavement furnaces?

Even Seven Devils Warn Against Using Coal Tar Sealants!

The Town of Seven Devils warns against the use of coal tar pavement sealants.  Located in the beautiful Blue Ridge Mountains of North Carolina, Seven Devils is surrounded by local, state and national preserves and parks.  Their website says:

Coal Tar Sealant Warning!!

Use of Coal Tar may be hazardous

to your health and the environment.

A link goes on to explain make the connection that they are a near neighboor to Boone, North Carolina that earlier this year imposed restrictions on the use of coal tar sealants because of a fish kill caused by washed-off coal tar sealant.  Some resources about the Boone Sealant Fish Kill are:

• Tar Heel Town Tackles Toxic Sealant