Asthma is a complex, multifactorial disease characterized by chronic airway inflammation, mucus secretion, airway remodeling, and reversible airway obstruction. Both genetic and environmental factors influence the development and exacerbation of asthma. More than 17 million people in the United States had asthma in 1998, double the incidence in the previous 20 years. Because the increase in asthma cannot be reconciled by changes in diagnostic categorization or by alterations in the gene pool, associations between asthma and the environment have attracted increasing attention. Since the Environmental Protection agency is required to set pollutant standards to protect susceptible populations such as asthmatics, a coordinated research to study environmental pollutants that influence the incidence and severity of asthma is needed.

"EPA 600-R-01-061." "September 2002." "On the cover: Asthma is a disease characterized by reversible airway obstruction, chronic inflammation, and airway remodeling. Susceptibility factors for asthma include the genetic background and overall health status of a person, as well as lifestyle, socioeconomic status, residential location, and overall exposure history, especially the potential for exposure to allergic induces and nonallergic triggers. The majority of asthma is associated with allergic responses to common aeroallergens in our indoor and outdoor environment, such as house dust mites, cockroaches, animal secretions, pollens, and molds. Exacerbation of asthma may occur with subsequent reexposure to allergens, or by exposure to a number of nonspecific triggers of lung inflammation and airway obstruction, such as respiratory viruses, tobacco smoke, or certain air pollutants." Includes bibliographical references (pages 29-30).