Almost a fifth of the country's population lives close enough to a high-volume road to see higher pollution levels from vehicle exhaust, according to a new study.
But a lack of nearby regulatory monitors could mean the federal government doesn't know the full effect of that pollution, said University of New Mexico engineering professor Gregory Rowangould, who conducted the census of near-roadway populations.
"We have all this great health research into some of these negative health outcomes of being near a roadway, but we didn't know just how big of a public health problem this might be," Rowangould said. "For it to be this large is surprising."
Rowangould's study, which will be published in the journal Transportation Research Part D: Transport and Environment, found that 19.3 percent of the U.S. population lives within 500 meters of a high-volume roadway, defined as one that carries 25,000 vehicles a day. The numbers were higher for low-income and minority populations, who may be unable to move away from the heavily trafficked areas.
Photo by Flickr user Ali Zeeshan Ijaz
The results were drawn from federal traffic data from 2008 and the 2010 and 2000 U.S. census.
Previous studies have shown that concentrations of pollutants from exhaust, including fine particulate matter, are higher near heavily trafficked roadways. That's associated with negative health effects, including asthma, respiratory problems and heart disease.
A recent study from the University of California, Los Angeles, and the California Air Resources Board found that roadway pollution can drift as much as a mile away in certain conditions.
Rowangould said his study also found that most counties with an affected population do not have an associated regulatory monitor near the roadway. States and counties have typically planted their monitors away from highways and congested areas because they are designed to measure pollutants across the entire region.
Moving monitors nearer to roads in a so-called hot spot, where the pollution concentration is traditionally higher, could leave some areas out of compliance with the National Ambient Air Quality Standards (NAAQS).
"You can't put a monitor everywhere, but placing them near the busier roadways should help," Rowangould said. "I have an issue with calling this a hot spot, because there are roadways everywhere. We know this is a large problem that affects a large portion of the population and in most places where there are people, there aren't monitors."
Starting next year, U.S. EPA will begin requiring that more than 100 cities begin tracking nitrogen dioxide levels near busy roads for use in compliance with the NAAQS. The monitors will be phased in through 2017 and will replace existing monitors in those regions but are expected to pick up higher pollution levels.
Angela Johnson Meszaros, general counsel for Physicians for Social Responsibility-Los Angeles, said the results of the latest study should put more pressure on the government to expand how it measures near-roadway pollution. PSR-LA was one of several groups that sued EPA last year to force more near-roadway monitoring.
"By having these numbers and making it real, the expansive impact of this problem can start to be measured," Meszaros said. "It allows us to move from the anecdotal layer to hard numbers and start to focus people's attention. We appreciate that EPA is starting to work on it, but now the obvious question is why even delay."
Rowangould cautioned that even with some limited monitoring, it will take deeper change to mitigate the impact of near-roadway pollution. Decades of either building highways near big cities or putting more development near new roads and highways has left much of the existing housing stock in high-concentration areas.
"Roads have come to people and people have come to roads," Rowangould said. "But now there's a greater awareness that living near busy roadways isn't a great idea. ... That puts a big burden on transportation planners to come up with plans to reduce exposure. It's a lot more difficult than, say, widening highways to increase traffic."
Reprinted from ClimateWire with permission from Environment & Energy Publishing, LLC. 202-628-6500.
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