Minor Pollution Increases Asthma Symptoms

Children with asthma have more respiratory symptoms and use more medications when the air’s ozone levels are elevated, even at levels that fall within the air quality standards of the U.S. Environmental Protection Agency (EPA), according to a new study in the Journal of the American Medical Association (2003;290:1859–67).

Asthma, an inflammatory disease of the respiratory system characterized by restricted breathing, has become more prevalent in children worldwide over the past two decades. An estimated 8.65 million children in the United States are now affected by asthma. Symptoms include wheezing, shortness of breath, cough, and chest tightness. Medical treatment includes the use of inhaled or oral steroids, antihistamines, other anti-inflammatory medicines, and inhaled bronchodilators. A severe asthma attack is a medical emergency.

The symptoms of asthma can be triggered by exposure to allergens or cold air, strong emotions, and exercise. In addition, exposure to high levels of air pollutants has been shown to aggravate symptoms in children with asthma. Studies have found that tobacco smoke, an indoor air pollutant, worsens asthma symptoms and might contribute to the initial development of asthma. Ozone and both fine and coarse particles suspended in outdoor air are pollutants that are known to increase asthmatic symptoms. The EPA has developed air quality standards based on safe levels of these pollutants, but recent evidence suggests that children with asthma experience increased respiratory symptoms at levels within these standards.

The current study investigated the relationship between outdoor air quality and severity of symptoms in children with asthma in southern New England over a 183-day period. Wheezing, persistent cough, chest tightness, shortness of breath, and medication use in 271 asthmatic children were recorded daily and compared with daily measurements of ozone and fine-particle levels. Participating children were divided into two groups for analysis: those who used maintenance medications and those who did not. Children who used maintenance medications were considered to have more severe disease and were found in this study to be more sensitive to ozone and fine particles than children who did not use maintenance medications.

Higher ozone levels significantly increased the incidence of respiratory symptoms in children using maintenance medications. Furthermore, the use of rescue medications (medications used to interrupt severe symptoms) in this group increased significantly with increasing ozone levels, even though the levels remained within EPA air quality standards. Adverse effects of higher ozone levels were not seen in children not using maintenance medications. Fine-particle levels were relatively low during the study period and were not associated with symptoms or medication use in either group.

The results of this study are consistent with others demonstrating that levels of outdoor air pollutants that are currently considered safe for the general population may cause problems in children with asthma. These findings suggest the need for tighter air quality standards and stronger efforts to reduce air pollution.

Maureen Williams, ND, received her bachelor’s degree from the University of Pennsylvania and her Doctorate of Naturopathic Medicine from Bastyr University in Seattle, WA. She has a private practice in Quechee, Vermont, and does extensive work with traditional herbal medicine in Guatemala and Honduras. Dr. Williams is a regular contributor to Healthnotes Newswire.

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