Study links California regulations, significant declines in cancer risk from exposure to air toxics

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GRA

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Of some relevance to the VW imbroglio, via GCC: http://www.greencarcongress.com/2015/09/20150921-arbtacs.html

A study by a team from the California Air Resources Board (ARB) has found that the collective cancer risk from exposure to seven toxic air contaminant (TACs) has declined 76% during the period from 1990 to 2012, and linked that result from air quality regulations targeting these TACs. The study appears in the ACS journal Environmental Science & Technology.

Of the seven TACs, diesel particulate matter (DPM) is the most important; DPM is emitted mainly from trucks and buses and is responsible for most of the airborne cancer risk in California, according to ARB. However, in the study DPM is not measured directly. Based on a novel surrogate method, DPM concentrations declined 68% during the period, even though the state’s population increased 31%; diesel vehicle-miles-traveled increased 81%; and the gross state product (GSP) increased 74%.

The nearly 70% drop in DPM coincided with actions taken over the years, beginning in the 1990s, to reduce diesel emissions. In the 1990s, California adopted a reformulated diesel fuel program; started a heavy-duty diesel truck roadside inspection program; implemented particle pollution standards for urban transit buses; and established standards for off-road diesel engines. In 2006, California began requiring ultra-low-sulfur diesel fuel.

Following the establishment of California’s statewide Truck and Bus Rule in 2008, California began requiring diesel particulate filters on trucks, reducing diesel particulate matter from the exhaust gas of diesel engines.

Based on monitoring data, concentrations of benzene; 1,3-butadiene; perchloroethylene; and hexavalent chromium declined 88–94%. (The reduction of benzene and 1,3-butadiene was largely the result of California gasoline reformulation in 1996, ARB said.) Also, the ambient and emissions trends for each of these four TACs were similar. Formaldehyde and acetaldehyde, which are formed in the air photochemically from volatile organic compounds (VOCs), declined only 20–21%.

The paper makes clear that further significant reduction in cancer risk to California residents is expected to continue as a result of continued implementation of air toxic controls. Such controls are part of broader statewide transportation initiatives, including the Truck and Bus Rule and more than a dozen rules focused on diesel equipment serving ports and railyards. Neighborhoods in freight corridors, including those near ports, will especially benefit. . . .
 
Here is an article from the BBC:
Concern over hidden diesel pollutant
"Atmospheric levels of a little known by-product from diesel engines are up 70 times higher than expected according to a study."
http://www.bbc.co.uk/news/science-environment-34347873
 
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