As environmentalists have pointed out, it can be as dangerous to be outdoors behind a city bus-walking, or bicycling-as it is to be in front of one. All the exhaust and smoke-even when they have been reduced by “clean air technology”-can damage a person’s health. The dangers of urban air pollution are of special concern to people who exercise by running, bicycling, or skating: these people, while trying to help their bodies through exercise, should take care that they don’t harm them through exposure to air pollution.
Dr. Joseph T. Cooke, Associate Professor of Clinical Medicine at Weill Cornell Medical College-and Associate Director of Medical Critical Care at NewYork-Presbyterian Hospital’s Weill Cornell Medical Center-says that air pollution is definitely a problem for those who work out in the city. “The main culprits are ozone, fine particulate matter, and carbon monoxide,” he says. “These pollutants irritate the lungs and respiratory system, and can exacerbate the problems of persons with underlying disease-whether respiratory disease such as asthma, bronchitis, or emphysema, or cardiopulmonary maladies.”
Especially if you have heart or lung disease, Dr. Cooke says, in summer, you should, if possible, exercise indoors, preferably in an air-conditioned room. “If you must go outdoors, the early morning or evening is best. It will be cooler, the sun is not at its peak, and the ozone levels will be at their lowest.”
Dr. Cooke says that epidemiologic studies have linked air pollutants to harmful effects on the heart and lungs, to emergency hospital admissions, and to deaths. The pollutants affect the lungs by causing inflammation or irritation of the airway lining. “More mucus and phlegm is produced,” he says, “and small muscles surrounding the airway respond by squeezing down. The work in breathing increases, and it becomes more difficult to get oxygen into the body.”
In addition to fine particulates-which are emitted by the diesel engines of trucks and buses-“The two most significant environmental culprits are carbon monoxide and ozone,” Dr. Cooke says. “Carbon monoxide arises from cigarette smoke and automobile exhaust. It has a tremendous ability to force oxygen out of our circulatory system-it combines with hemoglobin 200 times faster than oxygen. It is often fatal, and overexposure may lead to headache, dizziness, confusion, and dangerous increases in body temperature.”
Ozone, which is a large component of the smog found in cities like Los Angeles (and also New York), results from the interaction of sunlight and chemicals found in car exhaust. Ozone adversely affects a person’s breathing pattern. It causes the airways in the lungs to become smaller and more resistant to oxygen exchange. Because of ozone, a person working out has difficulty taking deep breaths, and has to breathe faster. As a result, the exercise becomes more stressful and difficult.
Dr. Cooke offers these simple tips:
1. Do not run on or near roads where there is heavy truck or bus traffic.
2. Work out in the early morning or later in the evening.
3. Exercise indoors if possible.
4. If you experience any difficulty breathing, stop your exercise immediately and see your doctor.
“By taking a few simple precautions,” Dr. Cooke says, “you can make your exercise a wholly good thing, and keep air pollution out of your body.”