Do you jog in smog? Air pollution is another factor to consider in your fitness program

American Fitness, May-June, 2002 by Paula Court

While enjoying your daily run on a sunny afternoon, a burning sensation suddenly grips your chest. What is going on? Could you be coming down with a cold? Probably not; you are most likely feeling the effects of exercising in air pollution. Recent research shows exercising in polluted air is harmful to your health. Air pollution interferes with the workings of your heart and lungs, aggravates asthma and weakens your body's ability to fight infections.

I'm in Great Shape, Why Worry?

Athletes are in an especially high-risk group, for the dangers of air pollution, because of the increased amount of air taken into their body during exercise. According to the American Lung Association, athletes take in up to 20 times more air per minute while exercising. Therefore, if air is polluted, 20 times more pollutants come in contact with an athlete's respiratory tract, reducing lung function and interfering with his or her performance. For example, exercising an hour in a moderate level of ozone and carbon monoxide can reduce lung function and temporarily decrease the blood's oxygen carrying capacity. Moreover, breathing through your mouth prevents your body from using its best defense against pollution--your nose. The nose filters air before it enters your lungs.

Pollutants

Ozone, the main hazardous ingredient in smog, forms when sunlight reacts with automobile and industrial emissions. As sunlight intensifies in the morning, the concentration of ozone increases. Ozone begins accumulating at approximately 11 a.m. and peaks around 3 p.m. After sunset, ozone can no longer form, therefore, the concentration decreases.

Ozone irritates breathing passages and can decrease the lung's working ability by damaging the cells lining the air spaces in the lungs. Damaged cells are shed and replaced but if this depletion occurs repeatedly, the lungs could become permanently damaged. High levels of ozone have been linked to increased emergency admissions in hospitals and recent studies released by the American Heart Association show the risk of having a heart attack when exercising at even low levels of air pollution.

Carbon monoxide, the main component of car exhaust, interferes with the body's ability to carry oxygen and forces the heart to pump harder. Other pollutants, such as nitrogen dioxide and sulfur dioxide, irritate the eyes, constrict air passages and lower the body's resistance to colds and other respiratory illnesses.

Reduce Your Exposure to Air Pollution

Several steps can be taken to reduce your exposure to air pollution without giving up your exercise program:

* Limit outdoor exercise to early morning or late evening--when ozone levels are low. "Hot, hazy days are the worst," says Joshua Fink, M.D., pulmonologist and medical director of Prescriptions for Fitness, Inc., in Chappaqua, New York. "Ambient ozone levels are higher and [irritate] the airways, resulting in bronchospasm and coughing," he explains.

* Check the newspaper for the ozone and weather report. The Environmental Protection Agency has developed the Air Quality Index (AQI) to report levels of air pollution. The AQI ranges from level 0 to 500. At levels over 100, limit strenuous outdoor activity. If the level reaches 200, air pollution is a serious health concern and exercising outdoors should be avoided. Levels above 300 rarely occur in the United States, but if this level should occur, discontinue all outdoor activity and stay indoors.

* Avoid exercising when air is thick and stagnant. Many athletes feel the effects of air pollution during outdoor exercise, but erroneously blame their shortness of breath on the heat. "Even a well-trained athlete should choose to exercise indoors on [smoggy] days," recommends Fink.

* If you jog outdoors, avoid congested streets. Remember, pollution levels can be high as far as 50 feet from the road.

* Include plenty of vitamin rich foods in your diet. Fruits and vegetables high in vitamin C and E have shown to protect lungs from pollutants. Vitamin C stimulates liver enzymes that detoxify the body and help prevent free radical damage in the lungs. Vitamin E stabilizes membranes and protects against free radical damage.

* When planning your workouts think seasonally--not daily. "To take away the worry about what's going on in the air day by day, change your exercise routine for the entire season," says Kevin Hamilton, B.S., RRT. "Develop a [seasonal] pattern depending on where you live." Save strenuous outdoor exercise activities, such as tennis and running, for clean air seasons. Also, move indoors for aerobics, racquetball and cross training during the summer.

Warning Signs

If while exercising you experience wheezing, coughing, scratchy throat, headache, chest pains, watery eyes or difficulty taking deep breaths, slow your pace. If this does not help, stop exercising and go indoors immediately. Most symptoms only last as long as you are exposed to pollution, but some can last for hours afterwards. People exposed to air pollution on a regular basis may experience the symptoms for the first few days and then the symptoms disappear. This does not mean the problem has gone away, in fact, pollution continues to damage the lungs even when symptoms are not present.