Asthma to a loaded gun and there are triggers that fire the loaded gun. The triggers of asthma can be divided into five groups: (1) airborne allergens, (2) nonallergic stimuli, (3) viral and bacterial infections, (4) chemicals and foods, and (5) psychological factors.
The best understood of all asthma triggers are the allergens pres¬ent in our indoor and outdoor air. These allergens set off reac¬tions when they are inhaled into the nose or lung. Airborne allergens such as dust, feathers, molds, insect parts, pollens, and animal parts or dander have several common characteristics. They must be small and light enough to remain airborne over long periods of time. Even a brief exposure to very tiny amounts of allergens will induce symptoms in a sensitized patient when these allergens are inhaled deep into the lung. Most such allergens can be identified by an allergy specialist using standardized skin and laboratory tests. Airborne allergens can be found in any environ¬ment: indoors, outdoors, at work, and at play. Some allergens, such as pollen, fluctuate with the seasons, while others, such as dust and mold, may be present in the air we breathe on a year-round basis
Environmental stimuli such as air pollution, chemical odors, hair sprays, cigarette smoke, and weather changes are all important asthma stimulants. These so-called nonspecific asthma triggers, widely dispersed in our environment.
VIRAL AND BACTERIAL INFECTIONS
Viral infections are among the most potent of all asthma triggers. One study showed that four out of every ten hospitalizations for childhood asthma are caused by common cold viruses. Different viruses strike different age groups. Infants and children are more susceptible to RSV and mycoplasma infection, while adult asth¬matics are more likely to be infected with the influenza or rhinovirus group.
Some recent clues help explain why many patients with allergies and asthma are prone to repeated colds and asthma relapses. Studies have shown that some people produce an allergic (IgE) antibody to certain viruses. Doctors also know that the common cold is more likely to be transmitted by hand-to-mouth contact than by droplets produced by coughing or sneezing. Many children (and some adults) with asthma and allergies have a per¬sistently itchy nose, which they constantly rub. This is a very ef¬fective way to transfer viruses from hand to mouth. The allergic salute may explain why so many asthmatics get one cold after another.