Found this article on the web
Urban Exercise Has Its HazardsAugust 26, 2006 08:41:10 PM PST
Yahoo! Health: Allergy News
SATURDAY, Aug. 26 (HealthDay News) -- Your intentions may be good, but exercising outdoors in a city may be riskier than you think, one expert says.
Outdoor activity can cause serious damage to a person's health because of elevated air pollution levels. Those especially at risk are those who exercise by running, bicycling or skating.
According to Dr. Joseph T. Cooke, associate professor of clinical medicine and patient safety officer at New York-Presbyterian Hospital/Weill Cornell Medical Center, the danger lies in the components of air pollution. The three main culprits are fine particulate matter, (the mixture of solid particles and liquid droplets in the air), ozone (a gas composed of three oxygen atoms) and carbon monoxide.
These components of air pollution irritate the lungs, making it harder to breathe and worsening problems initially caused by asthma, bronchitis, cardiopulmonary maladies, and emphysema.
"The pollutants affect the lungs by causing inflammation or irritation of the airway lining," Cooke explained in a prepared statement. "More mucus and phlegm is produced, and small muscles surrounding the airway respond by squeezing down. The work of breathing increases, and it becomes more difficult to get oxygen into the body," he said.
The three pollutants are located in cities around the world. Fine particulates are emitted from the diesel engines of buses and trucks. Carbon monoxide arises from cigarette smoke and automobile exhaust, and it has the ability to force oxygen out of a person's circulatory system.
For those exercising, overexposure to carbon monoxide can lead to dizziness, confusion, headaches and dangerously high body temperatures. Ozone, which is the largest component of smog in cities, adversely affects breathing patterns and decreases the size of airways, making the lungs more resistant to oxygen.
For those determined to work out outdoors, Cooke offered the following tips:
* Do not run on or near roads where there is heavy truck or bus traffic.
* Work out in the early morning or later in the evening.
* Exercise indoors if possible.
* If you experience any difficulty breathing, stop exercising immediately and see a doctor.
More information
For more on air pollution, visit The U.S. Centers for Disease Control and Prevention.