The epidemiology and genetics of asthma risk associated with air pollution.

The occurrence of asthma and allergic diseases has continued to increase in the United States and worldwide, despite general improvements in air quality over the past 40 years. This observation has led many to question whether air quality is truly a significant risk factor in the development and exacerbation of asthma and whether further improvement in air quality is likely to result in improved health outcomes. However, epidemiologic studies have shown that levels of pollutants of less than the current ambient air quality standards still result in exacerbations of asthma and are associated with other morbidities as well. Specific locations, such as living near a roadway, might pose a special exposure risk. Genetic factors almost certainly play a role in determining susceptibility to pollutants, such as including those involved with antioxidant defenses. The best studied of these in the context of air pollution risks are glutathione-S-transferase polymorphisms. Irrespective of whether pollutants contribute to the development of asthma or the well-documented increases in asthma results in more people having pollutant-induced disease, poor air quality in many places remains a significant problem for patients with asthma and allergic disease. A number of public health, pharmaceutical, and nutriceutical interventions might mitigate the effects of pollutant exposure and deserve further study.