Even Brief Ozone Exposure May Raise Fatal Heart Risk: Study

MONDAY, June 25 (HealthDay News) -- Even short-term exposure to ground-level ozone, a harmful air pollutant, can cause potentially fatal changes to your cardiovascular system, a new U.S. government study shows.

Ground-level ozone is created when pollutants from industry, vehicles, chemical solvents and power plants react in sunlight. Levels are highest in the hot, summer months.

The study, published June 25 in Circulation, "provides a plausible explanation for the link between acute ozone exposure and death," study lead author Robert Devlin, senior scientist at the U.S. Environmental Protection Agency's (EPA) National Health and Environmental Effects Research Laboratory in Research Triangle Park, N.C., said in an American Heart Association news release.

The EPA estimates that 40,000 to 50,000 people die in the United States each year because of air pollution, but the mechanism behind these deaths isn't fully understood.

For the study, researchers exposed 23 volunteers, between 19 and 33 years old, to a two-hour dose of ozone equivalent to the EPA's eight-hour ozone standard of 0.076 parts per million.

Within two weeks, the participants were also exposed to clean air for two hours. During both exposures, the young adults alternated between 15-minute intervals of rest and stationary cycling.

Although none of the participants complained of symptoms after inhaling ozone, tests immediately after exposure revealed the young people had serious ozone-induced vascular changes compared to clean-air exposure. These changes included:

  • An increase in a signature marker of inflammation that may play a key role in heart disease.

  • Reduced ability to dissolve blood clots that could block arteries.

  • Changes in heart rhythm.

The researchers noted these changes persisted until the morning after ozone exposure. They also pointed out the changes were reversible among these healthy young people.

However, the investigators said previous studies have shown that other air pollutants, such as tiny airborne particles known as particulate matter, may be linked to death in older people with heart disease. They suggested ozone and particulate matter may have similar, potentially deadly effects.

People can protect themselves by reducing their ozone exposure, the researchers advised.

You can do this by paying attention to air-quality alerts and limiting the time you are active outdoors when air quality is poor, they suggested.

More information

The U.S. Environmental Protection Agency has more on how to limit ozone exposure.

SOURCE: American Heart Association, news release, June 25, 2012

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