Allergens

There are many asthma triggers. Two large trigger categories are allergens and irritants. Allergens are substances that cause little problem for a majority of people, but will trigger an allergic reaction in sensitive people. During an allergy attack, the body releases chemicals called mediators. These mediators often trigger asthma episodes. Irritants such as cold air, cigarette smoke, industrial chemicals, perfume, and paint and gasoline fumes can trigger asthma. These irritants probably trigger asthma symptoms by stimulating irritant receptors in the respiratory tract. The receptors, in turn, cause the muscles surrounding the airway to constrict, resulting in an asthma attack.

The worst offenders of indoor environmental asthma triggers are predominately of the allergen category and include (but are not limited to): house dust, dust mites, cockroaches, molds, pets (any animals with fur or feathers), and pollen (tree, grass and weed). Irritants include (but again not limited to): second hand smoke, scented candles, air fresheners, ozone, and combustion by-products.

The EPA acknowledges house dust, dust mites, mold, mildew and other common indoor allergens trigger asthma episodes in sensitive individuals. Because Americans spend up to 90% of their time indoors, exposure to such indoor allergens (and irritants) plays a significant role in triggering asthma episodes.

For allergen avoidance information, click here.

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Common House Dust

House dust allergy is common even in clean homes. House dust is a major cause of year-round runny or stuffy nose, itchy, watery eyes and sneezing for allergy sufferers. Dust can also make people with asthma experience wheezing, coughing and shortness of breath. House dust is considered the worst offender of all the indoor environmental asthma triggers because it is a mixture of many substances. Its content varies from home to home, depending on the type of furniture, building materials, presence of pets, moisture and other factors. A speck of dust may contain fabric fibers, human skin particles, animal dander, microscopic creatures called dust mites, bacteria, parts of cockroaches, mold spores, food particles and other debris. A person may be allergic to one or more of these substances, and, if exposed to the dust, will have an allergic reaction.

Having a dust allergy is not necessarily a sign of a dirty house. Keep in mind, however, a dirty house can make a house dust allergy problem worse. Normal housekeeping procedures may not be enough to get rid of house dust and the resultant allergy symptoms. This is because many of the substances in dust cannot be removed by normal cleaning procedures. For example, no matter how vigorously you dust or vacuum, you will not reduce the number of dust mites present deep within carpeting, pillows and mattresses. Vigorous cleaning methods can put more dust into the air making symptoms worse.

In the United States, mold levels tend to peak during the summer months depending on where you live, since some tropical areas have molds year-round. There is also evidence that cockroaches have a seasonal pattern, peaking in the late summer. Dust mite populations tend to peak in July and August, and their allergen levels stay high through December. Mite allergen levels are lowest in late spring. Some dust mite-sensitive people report their symptoms worsen during the winter. That's because mite fecal particles and pieces of dead mites, both of which trigger dust mite allergy, are still present.

Forced-air heating tends to blow dust particles into the air. As the system drys out over the winter or times of low humidity, even more particles become airborne. Fewer symptoms occur during the summer possibly because the system becomes less dry due to humidity keeping much of the house dust in the system from becoming airborne. However, during the summer or in areas of high humidity, the collection of house dust in the system can build up to the point where it greatly effects the efficiency of the ventilation system to cool and circulate air in the home, resulting in high energy bills and increasing the possibility of your system breaking down.

If you think you may have an allergy to house dust, consult an allergist-immunologist.

For house dust reduction information, click here.

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Dust Mites

Dermatophagoides pteronyssinus and Dermatophagoides farinae, commonly known as house dust mites, are microscopic eight-legged creatures 0.3mm in length and invisible to the human eye. They are arachnids and relatives of spiders, not insects. Mites eat particles of skin and dander, so they thrive in places where there are people. A gram of house dust (approximately half of a teaspoon) contains as many as 1,000 dust mites. That same gram of dust can hold 250,000 of their fecal pellets. A dust mite will produce 20 fecal pellets per day, which is 200 times its own body weight in feces during its short lifetime. With millions of dust mites living in one bed, this means there are vast amounts of droppings there. These levels mean that virtually all dust mite-sensitive people will experience problems as a direct result of exposure to dust mites and their droppings in their mattress, pillows and duvet.

Dust mites are the largest offender in house dust worldwide and are the single, most important allergen associated with asthma. Thriving in humid, dark and warm environments, they prefer temperatures at or above 70 degrees Fahrenheit with a relative humidity of 75 to 80 percent. They will die if the humidity falls to below 50 percent and therefore are rarely found in dry environments. Dust mites make their homes primarily in pillows, mattresses, carpets and upholstered furniture, burrowing themselves deep into the fabric. Our homes are inundated with these microscopic, insect-like creatures and their debris, creating a hazardous environment for the allergy sufferer. It is virtually impossible to completely eliminate dust mites from your home, just as it is impossible to "cure" allergies.

As many as 10 percent of the general population and 90 percent of people with allergy-induced asthma are sensitive to dust mites. Recent studies in the United States suggest that at least 45 percent of young people with asthma are allergic to dust mites. Dust mites don't bite, cannot spread diseases and usually do not live on people. They are harmful only to people who become allergic to them. While usual household insecticides have no effect on dust mites, there are ways to reduce exposure to dust mites in the home.

For dust mite reduction information, click here.

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Molds

Molds are commonly found in outdoor air and greatly outnumber pollen grains. Outdoor airborne molds can easily invade your home. Any house can develop a mold problem, given the right conditions. You might not see it growing on the walls, but it may still be present in your home. Molds require two main factors to grow indoors: (1) free moisture that can occur in the form of relative humidity above 50 percent, leakage from pipes or foundations, clogged condensate or drip pans, or any ongoing source of water; and (2) something to grow on. Molds particularly like to grow on wallboard, wood or fabrics, but will grow virtually any place if they are given a chance. Molds spread by producing spores that can become airborne. These spores end up in house dust where they grow.

There are many different types of molds and, except for causing asthma symptoms in sensitive individuals, most molds are relatively harmless and easy to get rid of. However, there are some molds which are harmful to all individuals and an extreme case of contamination of even mild molds can cause symptoms in most people. Finding mold contamination early is the key. Molds thrive particularly in dark, warm, damp places. Be especially observant of kitchens, bathrooms, closets, basements, and crawl spaces. Contact a microbial remediation-certified service provider if you suspect you may have mold in your home.

For mold prevention information, click here.

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