Allergens: Allergens are anything to which people are allergic. In susceptible children, they may bring on an asthma attack. Allergens are also called triggers. Common allergens and stimuli include: dust, dust mites, mold, pollen, various grasses, animal dander, cockroaches and their droppings, and cigarette smoke. Other stimuli include cold air, abrupt changes in weather, strong emotions and exercise. (PG 2002.01)