A U.S. EPA report suggesting that Americans have significantly higher cancer risks because of toxic emissions from motor vehicles has reopened the debate over dangers posed by outdated diesel engines.
At issue is the National Air Toxics Assessment (NATA). Released Friday, the report draws on 2005 data to examine potential health risks from airborne toxics (Greenwire, March 11) and concludes that vehicle emissions -- including diesel exhaust -- pose significant health risks.
EPA's findings have raised tensions between environmentalists who say cancer risks posed by diesel exhaust is three times greater than risks from other airborne toxics and industry groups that maintain new diesel engines are among the cleanest on the road and diesel emissions are already heavily regulated.
Both sides agree, however, that more needs to be done to address the 11 million or so old diesel engines still in use. And both point to a government program for retrofitting diesel engines to reduce toxic emissions. However, Congress has put that program -- created by the Diesel Emissions Reduction Act (DERA) of 2005 -- on the chopping block in an effort to trim government spending.
"Despite 40 years of progress in moving toward cleaner vehicles, industrial sources and everything else, we still have a situation where every American faces a cancer risk due to airborne toxics," said Rich Kassel of the Natural Resources Defense Council. "To really move the needle on this problem, EPA has to address the diesel problem."
In its assessment, EPA found that all Americans have an increased cancer risk of greater than 10 in a million because of airborne toxics, the report says. To put that in context, EPA toxics regulations are drafted for substances found to present a cancer risk to greater than 1 in a million.
"This means that, on average," EPA wrote, "approximately 1 in every 20,000 people have an increased likelihood of contracting cancer as a result of breathing air toxics from outdoor sources if they were exposed to 2005 emission levels over the course of their lifetime."
Specifically, the report highlighted two substances in auto emissions as being particularly dangerous, formaldehyde and benzene, as well as diesel exhaust.
EPA did not calculate a cancer risk from diesel emissions because it said no specific unit risk estimate is available to do so. Instead, EPA focused on the effects of diesel soot or particulate matter on respiratory problems.
The report criticizes diesel in no uncertain terms.
"EPA has concluded that diesel exhaust is among substances that may pose the greatest risk to the U.S. population," the agency said.
Nonprofit, industry group spar over calculations
While EPA did not calculate diesel exhaust's cancer risk, an environmental group did.
The Clean Air Task Force (CATF) combined NATA data with the diesel cancer risk factor developed by the California Air Resources Board and found it to be three times greater than the risks of all air toxics tracked by EPA combined.
The Boston-based nonprofit also found that the average lifetime cancer risk from diesel exhaust to be 159 times greater than EPA's acceptable one cancer in a million standard for air toxics.
"The fact of the matter," CATF's Conrad Schneider said, "is that diesel is a risk almost everywhere because diesel engines are present everywhere. Not only is this one of the biggest problems, but it's one of the most widespread."
Diesel industry groups are pushing back against the EPA assessment and the environmental group's calculations.
Allen Schaeffer, the executive director of the Diesel Technology Forum, said NATA is based on 2005 data that do not take into account strides made by the diesel industry to clean up its engines.
"A lot of these are very retrospective views," he said. "In the diesel case, it's especially retrospective when you've had so much change so fast."
Specifically, Schaeffer pointed to developments since the 2005 diesel law.
New standards for engine emissions of particulate matter from trucks and emissions standards for off-highway vehicles have significantly reduced emissions, Schaeffer said. Further, new diesel engines have near-zero toxic emissions.
EPA failed to calculate a specific risk assessment for diesel exhaust because of the "complexities and uncertainties" of evaluating the toxic values of diesel exhaust, he said.
Schaeffer was also particularly critical of CATF's work.
"That's certainly not what we support in terms of how policy is made," he said. "It's just not how it's done."
In response, environmental groups counter that there are relatively few new clean diesel engines compared to old ones. Diesel watchdogs estimate that there are between 1 million to 1.5 million diesel engines in use that adhere to the strictest diesel regulations or have been retrofitted with effective emissions reducing filters.
Agreement on funding need
There is agreement between the diesel industry and environmental groups on one point: Federal funding for programs designed to retrofit older diesel engines so they produce less toxic emissions must be increased.
"We think the new engines are great," NRDC's Kassel said. "What we see here is data from 2005 showing that diesel particulate is a real problem. So ... the diesel cleanup should be funded."
The diesel law, which passed Congress with strong bipartisan support in 2005, authorized $1 billion in federal funding for five years to retrofit diesel engines with a filter that would reduce soot emissions by 90 percent or more.
But appropriators have never delivered the full amount of cash. Over five years, it has received slightly more than $500 million.
Congress reauthorized the law for $500 million over five years during the lame-duck session last year.
And President Obama included $300 million for the program in his economic stimulus package, but he zeroed it out in his proposed fiscal 2012 budget. House Republicans, who have been targeting EPA programs in their budget-cutting efforts, also proposed cutting $10 million from diesel engine retrofitting in their continuing resolution that passed Tuesday and is expected to be considered by the Senate today.
"I don't understand why anybody would want to cut that program," Kassel said. "There aren't a lot of really solvable environmental issues there. This is a 90 to 95 percent win. That's why it makes sense to prioritize it."
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