Asthma and Air Pollution: What's Happening in NIEHS Extramural Research

Article excerpt

Asthma is a chronic inflammatory disease with symptoms including reversible airway constriction, chest tightness, cough, and wheezing. The incidence of asthma is increasing and accounts for nearly 500,000 hospitalizations, 2 million emergency department visits, and 5,000 deaths annually in the United States. Asthma develops most commonly in children, although recent data suggest an increase in new cases among adults and the elderly.

An individual's risk for developing asthma is defined by a complex interaction of environmental exposures and hereditary factors. Risk factors include atopy or a predisposition to a Th2 immune response, diminished childhood microbe exposure, age at time of critical exposure, obesity, urbanization, and low socioeconomic status. In addition, numerous epidemiological studies have linked air pollution to exacerbation of acute asthma, increased use of asthma medication, increased school and work absence, and increased hospitalization. The NIEHS, recognizing these links and the persistence and continuing increase in air pollution globally, supports numerous research investigations that may provide keys to improved prevention and clinical management of asthma.

Toxicological research has characterized several components of air pollution, including particulate matter (PM), gaseous elements such as ozone, microbial products including endotoxin, heavy metals, and indoor and outdoor allergens such as house dust mite allergen and ragweed. Current NIEHS-sponsored extramural research targets pulmonary injury and dysfunction consequent to these exposures.

For example, researchers are examining the cellular and molecular pathways involved in oxidative stress induced by organic and metal-containing PM. Oxidative stress is a component of the inflammatory response and of airway hyperreactivity and asthma exacerbation. …