Microscopic metals and chemicals spewed from the tailpipes of vehicles traveling on highways are likely to harm the health of people who live nearby and spend significant amounts of time outdoors or with their windows open, according to a study released Wednesday by local public health researchers.
The study of so-called ultrafine particles is part of a growing body of evidence of the dangers of living near highways and other high-traffic roads. It suggests that those who live within 1,500 feet of a highway have a greater likelihood of developing cardiovascular disease than those living twice as far away. The Environmental Protection Agency estimates that more than 45 million Americans live within 900 feet of a major road, railroad, or airport.
The study, by researchers at Tufts University School of Medicine and Boston University School of Public Health, used special mobile labs in 2009 and 2010 to look at the impact of such microscopic pollution on residents of Somerville. The dangers of ultrafine particles are less understood than the impact of fine particles emitted by power plants and vehicles, which have been shown to increase asthma rates and are regulated by the EPA. There are no government limits on ultrafine particle emissions.
The authors said their study, which will be published this year in the Journal of Exposure Science and Environmental Epidemiology, is among the first to link cardiovascular risks to prolonged exposure of ultrafine particles, which include hydrocarbons and metals such as iron and nickel.
"The takeaway is that we need to begin to develop policies that protect people from these exposures, through improved air filtration, improved community design, decking over highways, and not putting children's playgrounds and bike paths near highways," said Doug Brugge, a professor of public health at Tufts University School of Medicine, who served as one of the authors.
The researchers took blood samples and interviewed 140 people from Somerville who live as close as a few hundred feet and more than a half mile from Interstate 93 and Route 38. They also adjusted for age, gender, body fat, and whether someone smoked, among other factors.
The researchers found that 115 subjects who lived within 1,500 feet of the highway had a median of more than twice the amount of C-reactive protein in their blood than the 25 who lived more than a half-mile away. Higher amounts of the protein indicate a higher likelihood of a stroke or heart attack.
The small scale of the study reflects on the need for more research and a wider sample size, said Kevin Lane, a research associate at the Yale School of Forestry and Environmental Studies, who conducted much of the research as part of his dissertation at the BU School of Public Health. But Lane said he hopes the findings of his work prod lawmakers to take action.
"This is an important study, because we don't have ultrafine particle standards, and if we want to get them, we need studies like this," Lane said. "This is the first of what needs to be a growing body of literature to drive this conversation."
Brugge said the findings also suggest that ultrafine particles could also pose a danger to people living near busy city streets.
He said the study found that the health risks of ingesting ultrafine particles are greater in the colder months, especially when the air is stagnant and blowing downwind during rush hour.
Further research is needed, he said, into whether it's counterproductive for people to exercise outdoors in such conditions.
Among the politicians paying attention to the study is Mayor Joseph Curtatone of Somerville. "I think we should all be concerned about the health risks," Curtatone said.
He said he hopes the findings will influence development decisions in Somerville, where he said the study should provide incentives to remove a major overpass on the McGrath Highway, improve air filtration devices in homes, and add highway sound barriers.
The data from Somerville, collected with a $2.5 million grant from the National Institutes of Health, are part of a broader study that looks at exposure to ultrafine particles of residents in Dorchester and Chinatown. The rest of the results will be published in a follow-up paper.