Air Pollution Linked to Higher Heart Attack Risk

Research from the relatively new field of environmental cardiology includes a 16-year-long Harvard University study of six U.S. cities that found fine particulate pollution, even at levels below the federal health standard, can shorten lifespans by two years. A majority of these earlier deaths were due to heart disease.

A study in Salt Lake City found that when a steel mill shut down for a period of months, there was a four to six percent drop in mortality in neighboring areas. The mortality rose to previous levels when the steel mill reopened.

A study of 250 metropolitan areas around the world found that a spike in air pollution is followed by a spike in heart attacks.

The people who seem to be most susceptible to environmental pollutants are those who are already vulnerable, including the elderly and people with coronary artery disease. There is some evidence that diabetics, women and people who are obese may be at greater risk.

Cardiovascular disease is the leading cause of death in the industrialized world. In the United States, it kills approximately one million people per year, accounting for over 40 percent of all deaths.

To examine this emerging research in greater detail, Aruni Bhatnagar of the University of Louisville and Robert Brook of the University of Michigan have organized a symposium called Environmental Factors in Heart Disease, to take place April 21 at an Experimental Biology conference in New Orleans. The 120-year-old American Physiological Society is one of the sponsors of the annual conference.

Dr. Bhatnagar, from the Division of Cardiology, Department of Medicine, University of Louisville, will speak on environmental aldehydes exposure and cardiovascular disease. His research shows that the risk of having a heart attack increases in parallel with time spent in traffic the previous day.

Joggers in San Francisco traffic inhale fine particles into their lungs. (Photo by Sharad Gupta)

Aldehydes are present in high concentrations in smog and are generated during combustion of any kind of organic material coal, wood, paper, or cotton. "Direct exposure to high concentrations of unsaturated aldehydes is cardiotoxic," writes Dr. Bhatnagar in a 2004 editorial in the "American Journal of Physiology."

The evidence strongly supports the view that "exposure to environmental toxins significantly increases CVD [cardiovascular disease] risk, which contributes to the overall health burden of air pollution," he writes.

Dr. Brook, an associate professor in the Department of Internal Medicine at the University of Michigan will speak on environmental pollution and hypertension. He has found that fine particles and ultra-fine particles entering the lungs can make their way into the blood vessels. Within 15 minutes of inhaling pollutants, there is a very rapid increase in blood pressure, he says.

Blood vessels react to the pollutants by producing an inflammatory response to attack the foreign particles. However, the inflammatory response itself can set off a complex physiological reaction that is harmful to the blood vessels, Dr. Brook says.

If you live in an area where pollution levels may be high, you can take steps to reduce the risk of air pollution, Dr. Brook advises. "During times when air quality is unhealthy, exercise indoors, because indoor air is filtered. If you exercise outdoors, particularly if you’re at risk for heart disease, do it when pollutants are at lower levels. Avoid peak traffic times," he says.

Other speakers at the symposium include Araujo Jesus of the University of California, Los Angeles, who will describe the the effects of ultrafine air pollution of blood vessels, and Murray Mittleman of the Harvard School of Public Health will speak on the connection between air pollution and strokes.

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