http://www.epa.gov/asthma/triggers.html
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Office of Air and Radiation, U.S. Environmental Protection Agency
Indoor allergens and irritants play a significant role in triggering asthma attacks. Triggers are things that can cause asthma symptoms, an episode or attack or make asthma worse. Work with your doctor to identify triggers and develop a treatment plan that includes ways to reduce exposures to your asthma triggers.