Heart attack survivors living close to highways face higher 10-year death risk

Writing in the May 7 edition of Circulation, researchers found heart attack survivors living less than 100 meters or 328 feet from a roadway have a 27 percent higher risk of over within 10 years than survivors living at least 1,000 meters away. That risk recedes to 13 percent for those living between 200 and 1,000-meter or 656 to 3,277-feet from the roadway.

"Living close to a highway is associated with adverse cardiovascular outcomes in those with underlying cardiac disease," says Murray Mittleman, MD, DrPH, a physician in the CardioVascular Institute at Beth Israel Deaconess Medical Center, an Associate Professor of Medicine at Harvard Medical School and director of BIDMC's cardiovascular epidemiological research program. "Besides air pollution, exposure to noise could be a possible mechanism underlying this association."

The Onset study of 3,547 heart attack survivors in 64 community hospitals and tertiary care medical centers recorded 1,071 deaths over 10 years. Of that total, 63 percent of the patients died of cardiovascular disease, 12 percent died of cancer and 4 percent expired from respiratory disease. Researchers analyzed factors such as personal, clinical and neighborhood-level characteristics such as income and education.

"People with lower levels of education and income are more likely to live in communities closer to a major roadway, so they are bearing a larger burden of the risk associated with exposure than people with more resources," says Mittleman.

In a study published earlier this year, a team led by Mittleman found air pollution, even at levels generally considered safe by federal regulations, increases the risk of stroke by 34 percent. Exposure to ambient fine particulate matter, generally from vehicle traffic, was associated with a significantly higher risk of ischemic strokes on days when the EPA's air quality index for particulate matter was yellow instead of green.

These finding provide new evidence that long-term exposure to roadways is associated with an increased risk of death in patients with underlying cardiovascular disease.

"Clinicians need to educate their patients on the risks posed by particulate matter pollution and encourage patients with cardiovascular disease to avoid unnecessary exposure to traffic," says Mittleman.

"On a public policy level, city planners should consider locating housing developments away from the most heavily trafficked roadways."

"This study adds to the growing knowledge linking roadways and traffic to health problems, even death, especially among those with pre-existent disease -- in this case a previous heart attack," says Dan Costa, ScD, DABT, National Program Director for Air Climate & Energy Research in U.S. Environmental Protection Agency Office of Research and Development Research.

In addition to Mittleman, co-authors include Joshua I. Rosenbloom, MPH, Elizabeth H. Wilker ScD, of the BIDMC Cardiovascular Epidemiological Research Unit; Kenneth J. Mukamal MD. MPH of BIDMC's Division of General Medicine and Primary Care; and Joel Schwartz, PhD of the Harvard School of Public Health.

The study was funded by the US Environmental Protection Agency and the National Institute of Environmental Health Science. Wilker was supported by a grant from the National Institutes of Health and Rosenbloom was supported by the Harvard Medical School Scholars in Medicine Office.