February 21, 2001
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Press Release

CDC study links improved air quality with decreased emergency visits for asthma

The Centers for Disease Control and Prevention (CDC) recently released a study showing that decreased citywide use of automobiles in Atlanta during the 1996 Summer Olympics led to improved air quality and a large decrease in childhood emergency room visits and hospitalizations for asthma. Atlanta’s inner-city children on Medicaid seemed to benefit the most from this Olympic experiment in city transportation planning, showing a 42% decrease in asthma-related emergency room visits. The study was released in the February 21st edition of Journal of the American Medical Association (JAMA).

Asthma is a substantial public health problem in the United States. It is a leading cause of childhood illness and can be life threatening. Some estimates show that the prevalence of asthma among children 18 years of age is as high as 6.9%.

"Many studies have shown a link between high air pollution days and worsening asthma symptoms which may lead to emergency room visits. But the impact of citywide transportation changes on air quality and childhood asthma had not been previously studied," said Michael Friedman, MD, epidemiologist in CDC’s environmental health program and lead author of the study. The alternative transportation strategy that Atlanta implemented during the 1996 Summer Olympic Games provided a unique opportunity to study this link.

During the Summer Olympics, strategies to decrease potential road traffic congestion problems were implemented, including closure of the downtown area to car traffic; increased access to public transportation through additional buses and trains; and promotion of flexible work schedules, car-pooling, and telecommuting for Atlanta workers. Cooperation between the Atlanta city government, Atlanta Committee for the Olympic Games, local businesses, local media, and residents contributed to the success of these strategies.

In this study, the authors found that automobile use decreased most dramatically during the weekday morning rush hour, that critical time of day when air pollutants typically build up, subsequently leading to elevated levels of ozone later in the day. Dramatic increases in public transportation use and widespread implementation of alternative downtown commuting schedules resulted in this observed decrease in automobile use.

The study compared data on the number of emergency medical visits for asthma and nonasthma-related conditions during the Olympic Games to a four-week period before and after the Olympics. Although some Atlanta residents left the city during the Olympics, the total number of emergency medical visits did not change during that period, while the number of emergency asthma visits decreased significantly. The study statistically linked the prolonged improvements in ozone and particulate matter pollution to a drop in emergency visits for asthma. The study also found that traffic pattern changes, rather than weather changes, seemed to account for most of the improved air quality in Atlanta.

"Our study is important because it provides evidence that decreasing automobile use can reduce the burden of asthma in our cities and that citywide efforts to reduce rush-hour automobile traffic through the use of public transportation and altered work schedules is possible in America," said Friedman.

Asthma is a very complicated disease with many possible causes. Air pollution resulting from automobile congestion is only one factor that may trigger an asthma event requiring emergency care. Therefore, efforts to decrease automobile emissions and improve air quality may not help everyone’s asthma. But this study demonstrates that the reduction of these emissions may have a significant impact on the overall public health burden of asthma, especially in the inner cities.

CDC protects people’s health and safety by preventing and controlling diseases and injuries; enhances health decisions by providing credible information on critical health issues; and promotes healthy living through strong partnerships with local, national and international organizations.

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