There are days, especially hot and smoggy summer days in the city, when you might step outside and wonder whether the "fresh" air you're breathing is safe. Doctors and researchers wonder the same thing. And more and more often, their research shows that there are times when the answer is "no". The culprit is ozone, a colorless gas that is good for you when found high in Earth's atmosphere but bad for you when found at ground level. Through the years, there's been a fair amount of coverage about the destruction of the good ozone layer that protects Earth. Increasingly, there's also more attention being paid to rising ozone levels at the Earth's surface. That means you may be breathing in more ozone, and that could mean trouble for your heart.

Ozone and Inflammation
Brian Kahn, M.D., F.A.C.C., Cardiologist at Mercy Medical Center in Baltimore, Maryland, explains that recent research on ozone and cardiovascular health has looked at its inflammatory effects. "Heart disease is really an inflammatory process," says Kahn. Inflammation is your body's response to infection and injury. For instance, if you cut your finger, the area will become red and inflamed as the body heals the wound. Your body may also have an inflammatory response to a number of factors such as cigarette smoking, diabetes, and, now scientists believe, exposure to high levels of ozone. If you already have plaque buildup in your arteries, this exposure could lead to the equivalent of a "chemical reaction," according to Kahn, "where all of a sudden plaques, which are not causing any problems, suddenly rupture."

The risks aren't just limited to those with arteriosclerosis, though. New studies show that anyone might be at risk for ozone-related cardiovascular problems.

The Elderly and Those With Health Problems
As you might guess, ozone exposure seems to be more dangerous if you already have plaque buildup in your arteries. There's a twofold reason for this: in addition to causing inflammation, ozone may encourage clotting. So if you're elderly, have heart disease, or are diabetic, you're already at greater risk for ozone-related inflammation which can cause plaque to rupture and arteries to narrow. Now, your system is going to be primed to start clotting (in an effort to heal the wound). It's those clots that block the arteries and cause heart attacks and strokes.

The Young and Healthy
The increased clotting should not be an issue for anyone who is in good health. However, a June 2012 study showed that ozone could still harm the hearts of healthy young adults. In fact, inhaling high levels of ozone equal those found in highly polluted cities (like Beijing or even Los Angeles) could cause inflammation and heart rhythm disturbances. These problems could become serious health issues over time.

Protecting Yourself from Ozone

If you spend time outside, especially if you're active outdoors for extended periods, you're more than likely going to be exposed to ozone. That fact doesn't mean you need to shut yourself up in the house 24 hours a day. But, if you're concerned about the dangers of ozone, you can adopt these "ozone smart" habits to limit your exposure:

  • Check ozone levels in your area. The EPA provides a daily Air Quality Index (AQI) for locations across the country at
  • Avoid peak ozone times. From mid-afternoon to early evening, ozone is at its highest, so you may want to avoid outdoor activities at those times.
  • Reduce ozone pollution. While industry and car pollution create most ground-level ozone, your actions can make a difference in your area, especially if you influence others to be more conscious of ozone emissions as well. Steps you can take include conserving household energy, driving less, and using fewer cleansers, paints, and other materials that are likely to release chemicals into the air.



"Environmental Protection Agency Ozone and Your Health." September 1999. Web. July 24, 2012

Raloff, Janet. "Ozone hikes cardiovascular risk." ScienceNews. 182.2:10 (2012). Web. July 24, 2012.