Originally published September 13 2006
Researchers Show How Air Pollution Causes Heart Disease (press release)
by NaturalNews, citizen journalist
New York University School of Medicine researchers provide some of the most compelling evidence yet
that long-term exposure to air pollution—even at levels within federal standards—causes heart disease.
Previous studies have linked air pollution to cardiovascular disease but until now it was poorly understood
how pollution damaged the body’s blood vessels.
In a well-designed mouse study, where animals breathed air as polluted as the air in New York City, the
researchers pinpointed specific mechanisms and showed that
can be particularly damagingwhen coupled with a high-fat diet, according to new
published in the December 21 issue of JAMA.“We established a causal link between air pollution and
,” says Lung Chi Chen, Ph.D.,Associate Professor of Environmental Medicine at NYU School of Medicine and a
author of the study.Atherosclerosis—the hardening, narrowing, and clogging of the arteries—is an important component of
.The study, done in collaboration with the Mount Sinai School of Medicine and University of Michigan,
looked at the effects of airborne particles measuring less than 2.5 microns, referred to as PM2.5, the size
linked most strongly with cardiovascular
. The emissions arise primarily from power plants andvehicle exhaust. The US Environmental Protection Agency (
) has regulated PM2.5 since 1997, limitingeach person’s average
per year to no more than 15 micrograms per cubic meter. These tinyparticles of dust, soot, and smoke lead to an estimated 60,000 premature deaths every year in the United
Dr. Chen and his colleagues divided 28 mice, which were genetically prone to developing cardiovascular
disease, into two groups eating either normal or high-fat
. For the next six months, half of the mice ineach feeding group breathed doses of either particle-free filtered air or concentrated air containing PM2.5
at levels that averaged out to 15.2 micrograms per cubic meter. This amount is within the range of annual
EPA limits and equivalent to air quality in urban areas such as
New York City
.The researchers then conducted an array of tests to measure whether the PM2.5 exposure had any impact
on the mice’s cardiovascular
. Overall, mice who breathed polluted air fared worse than thoseinhaling filtered air. But when coupled with a high-fat diet, the impact of PM2.5 exposure was even more
dramatic. The results added up to a clear cause and effect relationship between PM2.5 exposure and
atherosclerosis, according to the study.
On the whole, mice
polluted air had far more plaque than those breathing filtered air. In crosssections taken from the largest artery in the body—the aorta—mice on normal diets and exposed to PM2.5
19.2 percent filled with plaque, the fatty deposits that clog arteries. The arteries of thosebreathing particle-free air were 13.2 percent obstructed. Among high-fat diet mice, those exposed to
PM2.5 had arteries that were 41.5 percent obstructed by plaque, whereas the arteries of the pollution-free
mice were 26.2 percent clogged. In both normal and high-fat diet mice, PM2.5 exposure increased
cholesterol levels, which are thought to exacerbate plaque buildup.
Though findings for increased plaque among mice eating normal diets were not statistically significant, Dr.
Chen believes that future research on larger numbers of animals will solidify the trend. “Even with the
low-fat diet, there’s still something there. So that is something to think about,” he says. He suspects that
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PM2.5 exposure could also greatly affect even people who do not eat high-fat diets.
Mice exposed to PM2.5 also appeared prone to developing high
pressure, another element ofcardiovascular disease, because their arteries had become less elastic. To measure tension in the arteries,
the researchers tested how the neurotransmitters serotonin and acetylcholine affected the aortic arches of
PM2.5-exposed mice differently than those of controls. The arteries taken from exposed mice were less
elastic than the control group, constricting more in the presence of serotonin and relaxing less in response
to acetylcholine. Once again, the mice fed high-fat diets suffered the most pronounced effects from
breathing polluted air.
Finally, the researchers also examined various measures of vascular
, which is involved atherosclerosis on a number of levels. In the aortas of PM2.5–exposed mice, for example, they found increased levels of macrophages, immune cells that are an important ingredient in plaque deposits andalso active participants in a biochemical pathway related to inflammation. The study revealed several signsthat this pathway was more active, strengthening the connection between airborne particles and
The authors of the new study are: Morton Lippmann, Lung
Chen, and Ximei Jin of the NYU School ofMedicine’s Nelson Institute of Environmental Medicine, based in Tuxdeo,
; Qinghua Sun, AlexNatanzon, Juan-Gilberto S. Aguinaldo, Zahi A. Fayad, Valentin Fuster, and Sayjay Rajagopalan of the
Mount Sinai School of Medicine, New York; and Robert D. Brook and Damon Duquaine of University of
Michigan, Ann Arbor. The study was funded by the EPA and the National Institute of Environmental Health
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