An asthma attack can be triggered by a variety of allergens or irritants found both indoors and outdoors. When an asthmatic person breathes in an allergen or irritant, receptors found in the airway passages may be oversensitive to these particles. Binding of the particles to the receptors in the airway passages could lead to constriction of the airway from the surrounding smooth muscle. Another possibility could be inflammation of the airways, which would also result in the narrowing of the airway passages. People diagnosed with asthma should discover, with the help of their physicians, what allergens or irritants induce asthma attacks in their cases. Learning about these allergens and irritants can significantly reduce the severity and frequency of asthma attacks without the use of medications.

Indoor Allergens

Secondhand Smoke -- Over 4,000 compounds make up secondhand smoke, of which 40 are known carcinogens. Any of these compounds could potentially irritate the bronchial tubes of an asthmatic person and trigger an attack. Furthermore, many studies have shown how secondhand smoke increases the inflammation in the lungs as well as increases the prevalence of asthma in young children. Reducing exposure to tobacco smoke is advised to individuals diagnosed with asthma.

Dust Mites -- These microscopic organisms feed off of the skin that humans shed everyday. No matter how pristine a house may be, dust mites are present. Pieces of the dust mite as well as dust mite feces can cause an allergic reaction that leads to an asthma attack. Even though dust mites are present in every home, their populations can be reduced by washing bed sheets once a week with hot water and maintaining a low humidity indoors.

Mold -- Molds are microscopic fungi that can be found almost anywhere moisture is present. When mold produces spores, the spores can be breathed in and cause an asthma attack. It is not practical to try and eliminate all the mold in a household because mold can always be found floating in the air. The best way to control mold populations indoors, is to control the moisture indoors.

Pets -- A common allergen in many homes is caused by family pets. Pet dander, saliva, and feces can all produce allergic reactions in humans, which in turn lead to asthma attacks in humans. The simplest way to eliminate this source of asthma attacks is to never have pets in the home. If pets are removed from the indoor setting, vacuuming the carpets and upholstery is necessary to remove all the possible allergens leftover from the pet.

Nitrogen Dioxide -- This irritant is a by product of many gas appliances. In asthmatic people, even large concentration exposure to nitrogen dioxide can induce an asthma attack. Simple actions such as ventilation can significantly reduce the concentration of nitrogen dioxide indoors while cooking. It should also be mentioned that cars are also a primary source of nitrogen dioxide. Therefore, cars should not be kept idle within the garage, especially if an asthmatic person lives within the house.

Outdoor Allergens

Pollen -- For many asthmatic people that are allergic to pollen, the frequency and severity of their asthma attacks coincide with the fluctuations of pollen levels in the area. In some cases, allergy shots have been shown to reduce the frequency of asthma attacks. Further prevention of asthma attacks can be achieved through monitoring the pollen levels each day.

Pollution -- Pollution is an irritant that encompasses a wide range of substances found outdoors. In the case of smog, irritants can easily reach the sensitive lining of the bronchiole tube and lead to inflammation. In asthmatic people, the inflammation can be severe enough to lead to an asthma attack. Improving the air quality of that region is the only way to lower the concentration of this irritant.