Lower Asthma Incidence Linked to Reduction in Traffic

Efforts to reduce traffic congestion in Atlanta during the 1996 Summer Olympic Games may be associated with a reduction in area asthma-related emergency room visits during that same period, according to a new study by the CDC. Atlanta implemented an alternative transportation strategy during the 17 days of Olympic Games, including an all-day public transportation system, an additional 1,000 buses for "park-and-ride-services," alternative work hours for local businesses and closure of the downtown area to private automobile traffic. Researchers theorized that these traffic reduction strategies also reduced air pollution during the Games and consequently may have affected childhood asthma events. The study, published in this week's Journal of the American Medical Association, found that efforts to reduce traffic congestion were associated with a "prolonged reduction in ozone pollution and significantly lower rates of childhood asthma events." Comparing the 17 days of Olympic Games to a baseline period of four weeks before and four weeks after the Games, researchers found a 41.6% decline in asthma-related acute care visits among Georgia Medicaid claims files during the Olympics, and a 44.1% decline among HMO claims. In addition, asthma-related visits to two large pediatric emergency departments in Atlanta declined 11.1%, while citywide asthma hospitalizations decreased by 19.1%. Researchers also observed that overall emergency room visits and hospitalizations held steady during the two and-a-half week period (Friedman et al., JAMA, 2/21 issue).

On NPR's "Morning Edition," study co-author Dr. Michael Friedman of the CDC's respiratory health branch noted that previous studies have indicated an association between increased asthma symptoms during periods of high air pollution levels, but his study was the first to observe whether decreased pollution levels have an affect on asthma patients. Friedman said reduced traffic congestion and air pollution levels do "seem to matter," and the study findings "provid[e] people with ... a little bit of optimism to say there is something we can do about the air pollution levels, [that] it has been done at least once in America." Friedman added that the improved air quality "may have happened for only 17 days, but it's a starting point."

However, some critics say the "study on its own" is not proof that the lower pollution in Atlanta during the Olympic Games was "primarily due to reduced traffic," NPR's Joanne Silberner reports. Bob Shamidas, professor of atmospheric chemistry at Georgia Tech in Atlanta, said, "There's no question ... that the traffic was down during the Olympics. There's no question that a variety of indicators that we use for air quality showed better air quality during the Olympics. But the relationship between those two things ... is very, very unclear." Shamidas said other factors such as weather conditions could have "dispersed" asthma-inducing pollutants in the air during the Olympic Games. "To prove a connection, more variables would need to be considered," Silberner said. "For example, what was happening to the precursors to ozone, a major pollutant? How were these chemicals mixing in the atmosphere?" and were these changes related more to the changes in meteorology rather than in traffic?, Silberner asked. Shamidas also noted that the study gave no indication of how large a reduction in air pollution levels is needed to see an effect in asthma patients (NPR, "Morning Edition," 2/21). To listen to the NPR report, go to http://search.npr.org/cf/cmn/cmnpd01fm.cfm?PrgDate=02/21/2001&PrgID=3. Note: You must have Real Player G2 to listen to the report.