The environment and asthma in US inner cities

The prevalence and severity of asthma has increased in the last 20 years, a nd the greatest increase has been seen among children and young adults livi ng in U.S. inner cities. The reasons for this increase are obviously comple x, but include environmental exposures to allergens and pollutants, changin g patterns of medication, and the psychosocial stresses of living in poor i nner-city neighborhoods. This paper presents an overview of environmental, immunologic, and genetic factors associated with asthma morbidity and morta lity. This overview can be used to provide a framework for designing an int erdisciplinary research program to address the complexities of asthma etiol ogy and exacerbation. The strongest epidemiologic association has been foun d between asthma morbidity and the exposure of immunologically sensitive as thmatic patients to airborne allergens. Our current understanding of the pr ocess of sensitization suggests that there is a strong genetic predispositi on to form IgE to allergenic proteins on airborne particles. Much of this w ork has been conducted with animal models, but in a number of instances, sp ecific confirmation has been reported in humans. Sensitized individuals res pond to inhaled exposure with immediate mast-cell dependent inflammation th at may be augmented by pollutant particles, especially diesel exhaust parti cles. Relatively little is known about the methods of assessing exposure to airborne pollutants, especially biologically active particulates. However, to examine the relationship of morbidity in genetically predisposed indivi duals, it will be important to determine the most relevant method of making this assessment. Key words: air pollution, allergens, asthma, urban enviro nment.