Jan. 31, 2002 -- The frequency of asthma in children continues to rise, and pollution has been linked to asthma in previous medical studies. Now, a new study shows that kids who play outdoor sports in cities with high levels of pollution are more than three times as likely to develop asthma.
Asthma is the most common long-term disease of childhood, according to researchers in the medical journal The Lancet. Prior medical research has pointed to several possible reasons -- early-life infections, diet, exposure to indoor allergy-causing substances, and indoor and outdoor pollution.
Pollution is known to make breathing more difficult in children with asthma. But whether pollution can actually cause asthma is not known. This is particularly important in kids exposed to high amounts of pollution, such as during outdoor sports.
Researchers from the University of Southern California School of Medicine in Los Angeles studied more than 3,500 children to try to figure out the association between pollution, outdoor sports, and asthma. The kids -- who did not have asthma at the start of the study -- were from 12 different communities in southern California.
The children were followed for five years, and during that time, 265 children developed asthma.
Compared with kids that did not play any outdoor sports, kids that played three or more outdoor sports in communities with high amounts of ozone, a pollutant, were more than three times as likely to have asthma. In communities with low levels of ozone, sports had no effect on asthma.
Likewise, the more time spent outside in high ozone communities, the more likely the kids were to develop asthma. Time outside had no effect in low ozone communities.
The researchers conclude that the rising number of children with asthma is associated with heavy exercise in communities with high levels of ozone, said lead researcher Rob McConnell in a news release.
More studies are pointing to pollution as a possible contributor to the rise in asthma in the U.S. So the next question is, what can be done about it?
Rather than trading asthma for obesity, scientists need to figure out how to bring down the ozone levels. That seemed to make all the difference in this study.
In the meantime, if your child is having difficulty breathing, talk to you doctor about proper treatment and about the effect pollution may be having on your child's lungs.