Virtual forum on near-roadway air pollution highlights health effects
By John Yewell
Air pollution has long been a public health concern, and the spike in pollutants often detected near roadways is receiving closer attention from researchers and policymakers. NIEHS helped broaden public understanding of these impacts in the July 10 virtual forum, “Near-Roadway Pollution and Health,” moderated by Gwen Collman, Ph.D., director of the NIEHS Division of Extramural Research and Training (DERT). “Our presenters today come from the evolving robust network of air pollution researchers supported by NIEHS,” she said.
NIEHS and National Toxicology Program Director Linda Birnbaum, Ph.D., welcomed the more than 300 participants. “Today, we are focusing on air pollution near roadways and what effects that exposure may have on human health,” she said. The virtual forum allowed panelists to address questions sent in from across the country via email and Twitter.
Before the event, the four invited experts discussed their own research at a mini-symposium (see text box) sponsored by DERT:
- Joel Kaufman, M.D., from the University of Washington
- Toby Lewis, M.D., from the University of Michigan
- Rob McConnell, Ph.D., from the University of Southern California
- Veronica Vieira, Ph.D., from the University of California, Irvine.
Disproportionate effects on kids and minorities
The first question many participants asked about near-roadway pollution was how far from a major roadway did they have to live for the air to be relatively healthy. “As a rule of thumb, about 500 to 1,000 feet is a reasonably safe distance,” said McConnell.
According to a 2010 study by the Centers for Disease Control and Prevention, more than 11 million people live within 500 feet of a major U.S. highway. These residents may be more likely to be affected by the pollution, which is sometimes called traffic-related air pollution, or TRAP. The speakers noted that minorities tend to be disproportionately affected, and children are also at higher risk.
“Kids who live near the highways seem to have more respiratory issues than the kids who live further away,” Lewis said. A viewer with an asthmatic child asked how to choose a location for a new home. Besides living at a distance from major roadways, Lewis recommended using a HEPA air filter, because outdoor air enters the home, especially those without air conditioning. “You can create an environment that has less particulate matter," she said.
Lungs as gateway organs
Kaufman pointed out risks to organs other than lungs. “A large part of the burden of near-roadway air pollutants is actually on the cardiovascular system,” he said. McConnell referred to a July 7 paper in which he and collaborators estimated that the burden of cardiovascular disease attributable to particulate matter from traffic could be lessened by adoption of greenhouse gas reduction strategies.
McConnell pointed to other consequences. “There’s emerging evidence that it also has effects on the brain,” he said. “Evidence also shows correlations between near-roadway pollution during gestation and childhood obesity.”
Gauging and managing risk
Vieira discussed the complexities researchers face and advocated for use of personal monitors in studies. “A lot of times our exposure assessment methods [use] birth records or home address,” she said, pointing out that researchers do not always have information on travel, exercise, work, and other locations where study participants may spend time.
Measuring the risks is also no simple matter. Distance from traffic is important, but so are traffic volume, the types of vehicles, and the type of road, as well as meteorological conditions, such as wind, rain, humidity, and sunlight.
As for managing risk, “Good news!” said Birnbaum. “There are changes in policy and behaviors that are leading to cleaner air.” These include land use plans that reduce exposure to these pollutants, using filters in homes, schools, and workplaces, and increased use of fuel-efficient vehicles, carpooling, and biking.
The virtual forum was a collaboration among several NIEHS offices. “Pulling together this forum was joyful work,” said John Schelp, OSED special assistant for community engagement and outreach. “It takes a village to do a live broadcast, and collaborating with folks from DERT, OCPL [Office of Communications and Public Liaison], OD [Office of the Director], and contractors was great fun.”
Citations: Boehmer TK, Foster SL, Henry JR, Woghiren-Akinnifesi EL, Yip FY; Centers for Disease Control and Prevention (CDC). 2013. Residential proximity to major highways - United States, 2010. MMWR Surveill Summ. 62(Suppl 3):46-50.
Ghosh R, Lurmann F, Perez L, Penfold B, Brandt S, Wilson J, Milet M, Kunzli N, McConnell R. 2015. Near-Roadway Air Pollution and Coronary Heart Disease: Burden of Disease and Potential Impact of a Greenhouse Gas Reduction Strategy in Southern California. Environ Health Perspect [Online July 7, 2015; doi:10.1289/ehp.1408865].
(John Yewell is a contract writer for the NIEHS Office of Communications and Public Liaison)
Experts discuss their research on near roadway air pollution
By Kelly Lenox
At the mini-symposium, the invited experts shared insights from their research, including some preliminary findings. A look at the different studies they are doing shows the complexity of the task scientists face.
Kaufman and his colleagues are studying individuals in several cities, building upon the Multi-Ethnic Study of Atherosclerosis ( MESA). They are researching links between exposures to near-roadway pollution and changes in cardiovascular health over time. Kaufman reported that exposures vary greatly from one part of a city to another, and that as distance from traffic increases, concentrations of some pollutants, such as nitrous oxides, decrease more quickly than others, including fine particulate matter.
Lewis described a community-based participatory research project in Detroit studying the effects of education, air filters, and air conditioners on asthma severity among residents living near traffic sources. Lewis said that Michigan has a high rate of adult asthma, with higher rates of asthma-related hospitalization and mortality in low-income areas. Currently, they are seeing effective reduction in particulate counts and variations in how much the machines are used. The involvement of community groups is proving crucial to understanding usage patterns and collecting detailed data.
McConnell and his team are looking into how near-roadway air pollution affects rates of asthma and obesity in southern California. McConnell said that evidence is emerging that near-roadway pollution may cause asthma, especially in genetically susceptible children. Similarly, there is growing evidence of an association between such exposures and increases in body mass index, a common measure of obesity.
Vieira discussed her team’s use of satellite imagery to tease out links between fine particulate air pollution (PM2.5) and cardiac birth defects. By integrating data on PM2.5 levels and early gestation dates for babies born with such defects, they found that several conditions showed no association, and one, hypoplastic left heart syndrome, did show a possible link, prompting her call for further research. Vieira’s team is also looking at the incidence of infant bronchiolitis, a lower respiratory infection that may be affected by short-term exposures.