Keck School of Medicine of USC researchers, in collaboration with international partners in Spain and Switzerland and colleagues in California, have found that exposure to air pollution accelerates the thickening of artery walls that leads to cardiovascular disease.
The study, which will be published in the journal PloS ONE, is the first to link outdoor air quality and progression of atherosclerosis in humans.
Researchers found that artery wall thickening among people living within 100 meters of a Los Angeles highway progressed twice as quickly as those who lived farther away.
“The fact that we can detect progression of atherosclerosis in relation to ambient air pollution above and beyond other well-established risk factors indicates that environmental factors may play a larger role in the risk for cardiovascular disease than previously suspected,” said study co-author Howard N. Hodis, director of the USC Atherosclerosis Research Unit and professor of medicine and preventive medicine at the Keck School.
Atherosclerosis — or stiffening and calcification of arteries — is a condition that leads to heart attacks, stroke and related deaths. Animal studies conducted in recent years have shown that inhalation of particulate matter from traffic and other sources accelerates atherosclerosis, but there previously has been very little study of these effects on humans.
“Until now, no study has ever investigated whether the slow but chronic process of the development of atherosclerosis would be affected by ambient air pollution,” said study principal investigator Nino Kuenzil, vice director of the Swiss Tropical and Public Health Institute. Kuenzil began work on the study while a faculty member at the Keck School.
The findings were based on five randomized controlled trials — conducted by investigators at the Atherosclerosis Research Unit during the past decade — which involved linking the measured effects of outside air pollution to the progression of atherosclerosis in 1,483 participants in the Los Angeles area.
Colleagues at the University of California, Berkeley developed novel spatial models and air pollution measurements to estimate particulate matter all across Southern California and to estimate proximity from participants’ homes to high exposure zones near highways and traffic corridors.
The investigators found that annual progression of artery wall thickness among those living within 100 meters of a highway was accelerated by 5.5 micrometers a year, more than twice the average progression of people who lived farther away.
The findings support emerging evidence that high-traffic corridors are unhealthy residential locations, researchers said.
With funding from the National Institutes of Health and the Obama administration, through the American Recovery and Reinvestment Act, the investigators have launched two large studies examining the risk of ambient air pollution in the early development of atherosclerosis in children and young adults where cardiovascular risk factor is low, Hodis said.
“Should studies in children and young adults support our current findings in adult populations concerning ambient air pollution and atherosclerosis risk, the public health implications and preventive strategies for further reducing cardiovascular disease will have global implications for both developed as well as developing industrial nations,” he said.
The study was funded across six components of the National Institutes of Health.
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