Dear EarthTalk: Is it true that asthma cases in children often correlate to living close to roads and all the associated pollution-spewing traffic?—Jake Locklear, San Diego

Living near a roadway certainly does exacerbate asthma, especially for kids. To wit, a recent study by the University of Southern California (USC)—the most comprehensive by far to date on this topic—found that at least eight percent of the more than 300,000 cases of childhood asthma in Los Angeles County can be attributed to traffic-related pollution at homes within 250 feet of a busy roadway. The findings, released in the September 2012 online edition of the peer-reviewed journal, Environmental Health Perspectives, indicate that previous research underestimated the effects of roadway traffic on asthma.

“Our findings suggest that there are large and previously unappreciated public health consequences of air pollution in Los Angeles County and probably other metropolitan areas with large numbers of children living near major traffic corridors,” says Rob McConnell, one of the lead researchers on the study and a professor of preventive medicine at USC’s Keck School of Medicine.

“These findings confirm our understanding that air pollution not only makes things worse for people with asthma but can actually cause asthma to develop in healthy children,” reports Diane Bailey of the Natural Resources Defense Council (NRDC), a leading environmental non-profit. “It is even more sobering when you consider that 45 million Americans live within 300 feet of a highway and many of them are children.”

USC researchers note that new laws in California designed to reduce carbon output—improving fuel efficiency and reducing vehicle miles by increasing public transit options—will also help reduce asthma triggers. Some of the policies designed to reduce traffic congestion and car usage include offering housing developers incentives to locate projects closer to transit stops, thus encouraging use of public transit.

“Plans to reduce greenhouse gas emissions and combat climate change offer an opportunity to develop ‘win-win’ strategies that will maximize the health benefits from reduction both of greenhouse gases and of air pollutants that directly harm children,” McConnell says.

“There is also emerging evidence that other diseases may be caused or exacerbated by urban air pollution, including atherosclerosis, lung cancer, chronic obstructive pulmonary disease (COPD) and neurological disorders,” McConnell adds. “Thus, policies to combat climate change may have near-term health benefits beyond reducing the burden of disease due to asthma.”

According to NRDC’s Bailey, prioritizing the land directly next to freeways and other busy roads for commercial rather than residential use is one way to keep people at a safer distance from asthma-triggering pollution. Those who already live near busy roadways can help mitigate pollution effects by planting trees—foliage of all kinds is good at absorbing pollutants—and by filtering their indoor air to minimize overall exposure. But given that traffic pollution increases asthma by some eight percent, says Bailey, “we better do everything we can do reduce that pollution and minimize exposure to it.”

CONTACTS: Environmental Health Perspectives, ehp.niehs.nih.gov; NRDC, www.nrdc.org.

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4 Comments

1. 1. sault 03:41 PM 1/9/13

   To SciAm: Could you please post links to the journal articles that these articles are based? I found it after a few minutes of fooling around with Google Scholar, but most people will not go through the trouble even if they really want to see the whole paper. I'll help you out this first time:
   
   http://ehp.niehs.nih.gov/wp-content/uploads/2012/09/ehp.1104785.pdf

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2. 2. sault 04:20 PM 1/9/13

   As for the article itself, I don't think it's fair that either these children's parents or the government have to pay for the treatment of these health problems and not the people producing the pollution that causes them. Tax fuel and / or add in a charge to vehicle registrations to cover the costs of treating these current asthma cases AND preventing future ones.

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3. 3. Postman1 02:39 PM 1/10/13

   If you live in a city, and near a highway, you would be much less likely to have open windows or pets, or to spend much time outside. I have been told by Doctors for decades and read several times, that children raised in homes with pets, or on farms, are much less likely to contract asthma. Could the fact that the children in this study live in the city, plus that they are less likely to own pets near highways, contribute to these numbers? Maybe our attempts to live in a super-clean environment don't allow our immune systems a chance to build resistance to asthma and other diseases.

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4. 4. cindog 03:59 AM 1/22/13

   We live next to a freeway and found out next door neighbors had six cancers (four people and two animals). Does freeway pollution cause cancer or increase the risk? Half of the cancers are not hereditary. We plan to move soon.

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