Air pollution suffocates. Its effect on breathing is clear. But the impact of fumes, car exhaust and other particulates on other organs is less established.

A new study which appears in the April issue of PLoS Medicine found that long-term exposure to air pollution similarly suffocates our primary arteries, a condition linked to increased instances of both heart disease and stroke.

The leading cause of death among adults in the US is coronary artery disease—a cardiovascular disease in which the buildup of fatty deposits ("atherosclerosis plaques") within the heart's arteries slows blood supply, potentially causing a heart attack. Similarly, stroke—the fourth leading cause of death in the US—occurs when these fatty deposits block blood supply to the brain.

Researchers for the Multi-Ethnic Study of Atherosclerosis (MESA) took regular measurements of the thickness of the arterial wall, or the build up of these plaques, in 5,362 individuals while monitoring the concentration of fine particulate matter—such as produced by "motor vehicles, power plants, and other combustion sources"—at the patients' homes.

Their conclusion: That long-term exposure to fine particulate matter, or pollution, is associated with the progression of atherosclerosis and consequently with an increased risk of cardiovascular disease.

They write:

[W]e found evidence that individuals with higher long-term residential concentrations of [fine particulate matter] experience a faster rate of [thickening of the arterial wall] progression as compared to other people within the same metropolitan area. Improvements in air quality over the duration of the study were similarly associated with changes in [arterial wall] progression, with greater reductions in [particulate matter] showing slower [thickening] progression. These findings suggest that higher long-term [pollution] exposures may be associated with an acceleration of vascular pathologies over time.

“I think this provides us with even more evidence that air pollution is a cause of heart disease,” said lead author, Sara D. Adar, an assistant professor of epidemiology at the University of Michigan. “And it puts us one step closer to understanding how that happens.”

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