Poor, minority children living in US inner cities have increased rates of asthma morbidity and mortality. Factors that contribute to these increased rates are varied and complex, with current evidence suggesting that the environment is an important causative factor. Respiratory morbidity is often the result of allergens and air pollutants. Additionally, for children living in urban environments, underlying societal susceptibility factors specific to the inner city serve to increase asthma morbidity. Even though ambient pollutants have been declining in US cities, asthma morbidity and mortality rates have been increasing. Indoor pollutants are closely linked to increased asthma prevalence and morbidity. While the understanding of environmental influences is still relatively limited, we can say that indoor exposures are more important than ambient pollutants, and we know that bioaerosols containing allergenic proteins are especially important. Additionally, certain particulate aerosols and ozone cause inflammation individually and may act synergistically to enhance the acute and chronic IgE-mediated inflammation. The purpose of this article is to review the data relating exposure to environmental pollutants and airborne allergens, and the relationship of this exposure to asthma prevalence and morbidity in order to inform plans for public health programs to reduce an asthma burden.