Associations between criteria air pollutants and asthma
- Environmental Protection Agency, Chapel Hill, NC (United States)
The evidence that asthma is increasing in prevalence is becoming increasingly compelling. This trend has been demonstrated in the United States, the United Kingdom, New Zealand, Australia, and several other Western countries. In the US, the increase is largest in the group under 18 years of age. There is mounting evidence that certain environmental air pollutants are involved in exacerbating asthma. This is based primarily on epidemiologic studies and more recent clinical studies. The U.S. Clean Air Act of 1970 provides special consideration to the class of outdoor air pollutants referred to as criteria pollutants, including O{sub 3}, sulfur dioxide (SO{sub 2}), particulate matter (PM), NO{sub x}, CO, and Pb. Standards for these pollutants are set by the US EPA with particular concern for populations at risk. Current evidence suggests that asthmatics are more sensitive to the effects of O{sub 3}, SO{sub 2} PM, and NO{sub 2}, and are therefore at risk. High SO{sub 2} and particulate concentrations have been associated with short-term increases in morbidity and mortality in the general population during dramatic air pollution episodes in the past. Controlled exposure studies have clearly shown that asthmatics are sensitive to low levels of SO{sub 2}. Exercising asthmatics exposed to SO{sub 2} develop bronchoconstriction within minutes, even at levels of 0.25 ppm. Responses are modified by air temperature, humidity, and exercise level. Recent epidemiologic studies have suggested that exposure to Pm is strongly associated with morbidity and mortality in the general population and that hospital admissions for bronchitis and asthma were associated with PM{sub 10} levels. In controlled clinical studies, asthmatics appear to be no more reactive to aerosols than healthy subjects. Consequently, it is difficult to attribute the increased mortality observed in epidemiologic studies to specific effects demonstrated in controlled human studies. 106 refs., 1 fig., 1 tab.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 426049
- Journal Information:
- Environmental Health Perspectives, Vol. 103, Issue Suppl.6; Other Information: PBD: Sep 1995
- Country of Publication:
- United States
- Language:
- English
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