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Indoor Allergens

What to do about them?

Allergen exposure in the home is a major risk factor for the development of allergic diseases such as allergic rhinitis and asthma.  Since we spend 90 percent of our time indoors, and the level of pollutants are 2-5 times higher indoors than outside, a large proportion of the population is sensitized to one or more allergens that are found indoors. Assessments of allergen exposure are made by measuring major allergens in dust samples.  These allergens include but are not limited to dust mites, animal allergens, and cockroach allergens.


Dust mites

Many individuals are allergic to house dust.  Dust mites live in the dust that accumulates in most homes, particularly within fabrics.  Favorite habitats for dust mites include carpets, upholstered furniture, stuffed toys, mattresses, pillows and bedding materials.  Their major source of food is shed human skin scales, which are present in high numbers in most of these items, and the allergens are contained in the fecal particles that accumulate in their habitats.   Dust mites prefer a warm and humid climate and their growth can be controlled by keeping the relative humidity below 40 to 50 percent.  Measures to reduce mite allergen in the home include encasing mattresses and pillows with tightly woven materials that prevent penetration by mites as well as their fecal particles.  Bed linens should be washed in hot water every 1-2 weeks.  It is prudent to remove carpets and soft furnishings, especially from the bedroom, to reduce potential mite habitats. 


Animal allergens

Household pets are the most common source of allergic reaction to animals.  Researchers have found that the major allergens are proteins secreted by the oil glands in animal’s skin and shed in dander, as well as proteins in saliva which stick to the fur when the animal licks itself.  Urine is also a source of allergy-causing proteins.  When the substance carrying the protein dries, the protein can then float into the air.  Due to this characteristic as well as the fact that particles carrying cat and dog allergens appear to be very sticky, animal allergens can be found in significant levels even in homes or workplaces that never housed the animal. 

Some rodents, such a guinea pigs and gerbils, have become increasingly popular as household pets.  They, too, can cause allergic reactions in some people, as can mice and rats.  Urine is a major source of allergens from these animals.

Animal allergens can be controlled by finding a new home for the pet.  Relief should not be expected for weeks or months after removal of the pet, as particles remain airborne and distributed over the entire home.  Aggressive cleaning may help to reduce the reservoirs of the allergen.  If the pet is not removed, HEPA or electrostatic filters should be installed, especially in the bedroom, carpeting should be removed and mattress and pillow covers should be replaced. 


Cockroach allergens

Cockroach allergens are proteins found in the insect’s feces, saliva, eggs and shed cuticles that can trigger allergic reactions when they become airborne and are inhaled by humans.  Cockroach allergens produce allergic effects particularly in children, including respiratory symptoms and especially asthma.  Cockroach allergen in the home can be reduced by regular and thorough extermination of the infestation, followed by thorough cleaning.  Neighboring apartment dwellings should also be included in the extermination program.  In order to reduce the likelihood of further infestations, leaky pipes and faucets, holes in the wall and other entry points should be repaired.  Behavioral changes should be made to reduce the availability of food sources that attract cockroaches, such as cleaning up immediately after cooking, avoiding open food containers and uncovered trash cans.


Allergen testing

Our indoor air quality specialists will collect dust samples from three or four sites in the home, including mattresses, bedding, bedroom or living room carpet, soft furnishings or kitchen floors, by vacuuming each area for two minutes and collecting the dust into a special filter.  The composite dust sample is then sent to a laboratory for analysis.  For allergen exposure assessments up to 8 common allergens can be analyzed including dust mite allergens, animal allergens of cat, dog, rat, and mouse, as well as cockroach.  Based on the test results, corrective action can be taken to reduce occupant exposure to the allergens.