Airborne bacteria exacerbate attacks.

• Position: Asthma

Endotoxin, a bacterial substance commonly found in outdoor and indoor air, makes mite-allergic asthmatics more sensitive to house dust and may place them at increased risk of asthma attack. These research findings from the University of North Carolina at Chapel Hill School of Medicine are consistent with previous UNC studies showing that exposure to ozone causes asthmatics to become more sensitive to allergens, the environmental triggers of allergic reactions. Ozone and endotoxin are not allergens; however, they can cause portions of the respiratory tract to become inflamed.

Endotoxin is a complex of lipids (fats) and sugar molecules that is released through the outer cell wall of common bacteria. When the bacteria die, the cell wall collapses and endotoxin escapes into the environment, "We know that asthmatics can have asthma attacks triggered by various environmental exposures, but we don't always know why certain circumstances precipitate asthma attacks when there are no clear cut exposures to the allergens they are sensitized to," indicates Brian A. Boehlecke, professor of medicine in the Division of Pulmonary Medicine and member of the Center for Environmental Medicine, Asthma and Lung Biology.

"Now it appears that various airborne irritants such as ozone and endotoxin, which can cause airway inflammation, may interact synergistically with other causes of airway problems, including allergens, to make asthma worse."

The study involved 14 participants with mild asthma for whom skin testing revealed...