Inhaling a Heart Attack: How Air Pollution Can Cause Heart Disease

University of Michigan tests show short-term exposure to fine particle air pollution
can drive up high blood pressure, raise risk of heart attack.

It's well known that measures such as exercise, a healthy diet and not smoking can
help reduce high blood pressure, but researchers at the University of Michigan Health System
have determined the very air we breathe can be an invisible catalyst to heart disease.

Inhaling air pollution over just two hours caused a significant increase in
diastolic blood pressure, the lower number on blood pressure readings,
according to new U-M research.

The study findings appear in the current issue of Hypertension, a publication
of the American Heart Association.

Nearly one in three Americans suffer from hypertension, a significant health
problem that can lead to heart attack, heart failure, stroke, and other
life-threatening problems.

"Although this increase in diastolic blood pressure may pose little health
risk to healthy people, in people with underlying coronary artery disease this
small increase may actually be able to a trigger heart attack or stroke," says
Robert D. Brook, M.D., lead author and vascular medicine physician at the U-M
Cardiovascular Center.

In the study, researchers hoped to identify which air pollutants are harmful
and how the pollutants work to damage the cardiovascular system.

Eighty-three people in Ann Arbor and Toronto were involved in testing and
breathed air pollution, concentrated by a mobile air quality research
facility, that was similar to what would be found in an urban environment near
a roadway.


"We looked at their blood vessels and then their responses before and after
breathing high levels of air pollution," explains Robert Bard, M.S., overall
research project manager.

Ozone gases, a well-known component of air pollution, were not the biggest
culprit. Rather, small microscopic particles about a 10th of the diameter of a
human hair caused the rise in blood pressure and impaired blood vessel
function, tests showed. The blood pressure increase was rapid and occurred
within two hours, while the impairment in blood vessel function occurred later
but lasted as long as 24 hours.

It's believed these fine particles deposit deep into the lungs and certain
components may gain entrance to the blood stream, or cause an inflammatory
response throughout the body.  There is also evidence that functions in the
body's nervous system are also disrupted.

The research is the latest in the relatively new field of Environmental
Cardiology which looks at the association between air pollution and heart
disease. Brook says that at the very least the findings support efforts to
maintain current ambient air quality standards set by the Environmental
Protection Agency.

"It really bolsters and strengthens the importance of maintaining air quality
for human health," says Brook.

There are practical ways to avoid exposure to high levels of air pollution,
such as avoiding unnecessary travel or commutes and not exercising during rush
hour, or near busy roadways, Brook says. In modern society, the burning of
fossil fuels is the primary source for air pollution.

"If air pollution levels are forecasted to be high, those with heart disease,
diabetes or lung disease should avoid unnecessary outdoor activity," he says.


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