Breathing polluted air found in urban areas promotes heart disease, especially when accompanied by a fatty diet, researchers who tested the theory on mice said on Tuesday.
The animal study was aimed at determining how air pollution — specifically small airborne particles spewed by car exhaust and power plants — combined with a high-fat diet sped up the deterioration of the body's cardiovascular system.
"We established a causal link between air pollution and atherosclerosis," said the study's lead author, Lung Chi Chen of New York University's School of Medicine.
Airborne particles smaller than 2.5 microns across — 1/40th the width of a human hair — are believed to penetrate deep into the lungs and damage the body's cardiovascular system, exacerbating the buildup of plaque that narrows arteries and makes them less flexible and prone to inflammation. Such deterioration makes people ripe for a heart attack or stroke.
Some estimates blame the tiny airborne particles from dust, soot and smoke for 60,000 premature U.S. deaths each year, according to the report published in the Journal of the American Medical Association.
In the six-month study, which was funded in part by the U.S. Environmental Protection Agency, 28 mice bred to be susceptible to cardiovascular disease were divided into four groups.
The mice that breathed air polluted with 15 micrograms per cubic meter of small particulates — comparable to the air quality in urban areas like New York and within EPA limits — fared worse than mice that breathed clean, filtered air.
The arteries of mice that breathed bad air and were fed a high-fat diet were 42 percent blocked with plaque. Those that were fed a high-fat diet but breathed clean, filtered air were 26 percent blocked. Blockages were also apparent in mice fed a normal diet, with polluted air increasing the amount of plaque.