Asthma is characterized by recurrent wheezing, breathlessness, chest tightness, and coughing. Research in the past decade has revealed the importance of inflammation of the airways in asthma and clinical treatment to reduce chronic inflammation. Asthma is associated with production of IgE to common environmental allergens including house dust mite, animal dander, cockroach, fungal spores, and pollens. Some interventions to reduce symptoms through control of dust mite and animal dander have had positive results. Control of symptoms through interventions to reduce exposures to cockroach antigen has not been reported.
Studies illustrating causal effects between outdoor air pollution and asthma prevalence are scant.
Increases in asthma prevalence have occurred at the same time as general improvements in air quality. However, air quality appears to exacerbate symptoms in the child who already has the disease. Decreased pulmonary function has been associated with exposure to particulates and bronchial hyperresponsiveness to smoke, SO 2 and NO 2 . Symptoms have been correlated with increased levels of respirable particulates, ozone, and SO 2 . Interventions that reduce the negative outcomes in asthma associated with outdoor environmental factors have not been reported.