Athletes, fitness enthusiasts and outdoors workers may be doing more health damage than good if the air they breathe is polluted.
Exercising in polluted air may cause tightness in the chest, coughing, wheezing and even more long-term effects, according to the Lung Association.Exercise makes people more vulnerable to health damage from pollutants because they breathe deeper and take in more air.
In fact, the purpose of exercise is to improve the body's ability to deliver oxygen. Exercise may increase air intake by as much as 10 times. But this means that exercising in polluted air increases contact with pollutants and chances for health damage.
And during heavy exertion, people breathe through the mouth, bypassing the body's first line of defense against pollution - the nose.
The association warns outdoor exercisers to be conscious of smog levels during warm weather.
Because sunlight and time are necessary for ozone smog formation, the highest smog levels typically occur during the afternoon. Fitness enthusiasts should exercise in the early morning or evening and avoid afternoon exercise or strenuous outdoor work.
Dr. Ken Buchi, chairman of the Wasatch Clean Air Coalition, said the peak levels of ozone correlate with traffic and heat. The pollution level is higher during the 7:30 a.m. to 10 a.m. rush hour, but is even higher during the 4 p.m. to 6 p.m. evening commute because temperatures are higher, he said.
On days when the pollution is at dangerous levels, people either should not exercise or should exercise indoors, the association cautioned. The possible damage may far outweigh any benefits.
When exercising, stay at least 30 to 50 feet away from cars. At traffic lights, move ahead of the exhaust pipe of the first car, or stay behind the last car until the light changes.
Buchi said ozone is the pollutant of major concern. Ozone smog tends to be worse between May and September when joggers and cyclers are more likely to train outdoors.
Children, asthmatics, heart and lung disease sufferers and elderly people are already vulnerable to air pollution and are even more vulnerable when exercising or working outside.
Buchi said normally healthy people do not need to modify what they do, but those who suffer from respiratory ailments should be more careful.
According to the Lung Association, children are especially at risk because for their size they breathe more and faster than adults. Also, children spend more time outdoors and are likely to be more active.
Children and youths are at risk also because sports and outdoor school activities tend to be held when smog levels are the highest.