Category: Allergens  

Environmental Allergens

Allergen Description Helpful Hints

Dust Mite
Small Dust Mite

See a larger & uglier dust mite

Dust mites are microscopic insects related to spiders and are the indoor allergens to which most allergy and asthma patients are sensitized. They require greater than 50% humidity to survive. Their diet consists mostly of the dead skin cells shed by humans and animals. Dust mites are commonly found in bedding, upholstered furniture and carpeting. The dust mite feces is the major allergen. It is usually only airborne when dust is disturbed during cleaning.

Learn more about dust mites.

If you’re curious, you may purchase an inexpensive kit to rapidly analyze the dust of your home for dust mites or a more comprehensive test kit for indoor allergens including molds.

To be clinically effective, the exposure to dust mites must be reduced by at least 90%. Aggressive measures will help asthmatics.


  1. Impermeable dust mite covers (for pillows and mattress)
  2. Wash bedding in hot water (130° F)
  3. Maintain Humidity below 45% by use of dehumidifier

Also Helpful

  1. Removing Carpeting (polished floors are best)
  2. Washing carpeting with chemical treatments may temporarily work but inhalation of the powders can make asthma worse

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Cat protein is a very “sticky” allergen. Like cat hairs, it clings to clothing and can be carried to work and school. As a result, cat protein levels can be measured in places where a cat has never been. Some schoolchildren who have never touched a cat have become sensitized through such exposure. Cat protein is very light and can remain airborne for prolonged periods. Also, because allergen levels will remain high for up to six months after removal of the cat, improvement in symptoms is a gradual process. Contrary to popular belief, there is no such thing as a “hypoallergenic cat.” Even hairless Sphynx cats still shed skin and urine proteins that cause allergies. Get more information. There is no replacement for eliminating the cat from the home. However, you may benefit from:

  1. Use a HEPA air filter.
  2. Keep cat out of bedrooms.
  3. DO NOT allow cat to sleep beside you.
  4. Have someone else do your dusting and air out the room afterward.
  5. Washing the cat at least weekly has been shown to reduce allergen levels but it is unclear if this helps patients. It’s not easily done.
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If you are visiting a home where cats reside:

  1. You may benefit from taking medication beforehand.
  2. Use a tape roller for removing pet hair from clothing so you don’t bring the cat dander home with you.

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Cockroaches are the #1 cause of allergy in the inner city. The cockroach protein is fairly heavy and is usually airborne only during sweeping. Read more.
  1. Wear a mask while cleaning.
  2. DO NOT use roach sprays as these may cause severe asthma attacks.
  3. Use roach control devices such as Combat or boric acid.


Dog allergy, can also cause severe symptoms. Perhaps because dogs are easier to bathe and urinate outdoors, allergy may be somewhat easier to control than cat allergy. Just because you’re allergic doesn’t mean you can’t have a dog. See a discussion about this at Dogbiz. Same as for cats

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Molds may be indoor or outdoor allergens. Damp environments promoting their growth include bathrooms, kitchens, basements or any area where a leak had occurred. Outdoor molds are present through most of the year but tend to peak in the fall months as they grow on decaying leaves. More information may be found at the NYC Department of Health Guidelines for Mold Identification & Remediation or read general information about allergies and mold. Read about how to distinguish mold growth from other discolorations. Controlling humidity and leaks helps reduce likelihood of mold growth. Once established, molds must be attacked at the source. If property is musty or stained it should be removed. Mold growth on shower walls or other washable surfaces can be treated with a dilute bleach solution (1 part bleach to 2 parts water) or with any number of commercial cleaners.


In New York, there are 2 distinct pollen seasons occurring in the spring and fall. With the first signs of spring, tree pollens cause most allergy symptoms. Grass emerges in the late spring (May-June) as tree pollen counts are diminishing. Ragweed is the major fall pollen– the season begins in late August and continues for weeks typically until the first frost. Read general information about pollen counts. When going outdoors, remember that pollen levels are highest in the morning, and gradually subside as the day goes on. You can obtain pollen counts and daily allergy alert email from For locals, we have the New York City Pollen count as well as links to NY air quality reports.
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