For a printable version (pdf) of this
fact sheet, click here
What are indoor allergens?
Indoor allergens are biological or chemical substances that trigger the immune system,
causing an allergic reaction. Biological sources of allergens include pets, insects, dust
mites, plants, bacteria, and mold. Chemical sources are often gases or particles released
by items such as building materials, fabrics, glues, paints, solvents, dyes, and perfumes.
How can I be exposed to indoor allergens?
The most common way to be exposed to indoor allergens is by breathing them. Exposures
can also occur if allergens are ingested, or if they come into contact with the skin or
eyes. All buildings contain indoor allergens because there are so many different sources.
For instance, pet hair, dust mites, cockroaches, and mold are common sources of indoor
Outdoor plants can contribute to indoor allergens by releasing pollen that then enters
buildings. Hay fever is an allergic response to grass pollen. Chemicals can also act as
allergens. Metals, perfumes, dyes, and solvents found in common household products such as
carpet, upholstery, laundry detergents, and paints can cause symptoms in people.
What are the effects of exposure to indoor allergens?
An allergic reaction develops when a person who is sensitive to a particular substance,
comes into contact with that substance. Exposures to an allergen can cause a runny nose,
sneezing, coughing, difficulty breathing, skin rashes, and watery eyes.
Severe allergic reactions can be life threatening and require immediate medical
treatment. Sensitivity to allergens varies between people; for instance, some people are
allergic to cats, while others are not. Exposure to other chemicals (e.g., tobacco smoke),
in addition to the allergen, can sometimes worsen the symptoms. Repeated or long exposure
to the allergen will often make the symptoms worse.
How can I avoid being exposed to indoor allergens?
- Find out which allergens are bothering you by visiting your doctor. After you identify
the allergen, remove the source to prevent further reactions.
- Keep your home clean of mold, cockroaches, and dust. Keep areas dry and clean, such as
bathroom window sills, basements, and refrigerator doors.
- Keep the relative humidity level in your home between 30-50%. This helps control the
growth of dust mites and mold.
- Vacuum regularly in order to eliminate allergens in dust. Special vacuum bags (HEPA
filter) can be used to control small dust particles and prevent them from re-circulating
back into rooms.
- Wash bed sheets in hot water every 7 to 10 days to kill dust mites. Impervious mattress
covers will help keep dust mites from getting inside mattresses.
- If you are sensitive to pollen, keep windows closed to reduce the amount of pollen that
enters your home.
- Use unscented or low-odor detergents and paints to reduce exposure to chemical
- Hard-surfaced floors and simple window coverings make it easier to control dust levels
in your home. Machine washable throw rugs can be cleaned frequently to remove dust and
- Use fiber-filled pillows instead of feather-filled pillows.
- Food allergies may increase sensitivity to indoor allergens (e.g. Some people are
allergic to certain foods, like peanut butter, chocolate, wheat, or milk).
- For information on the use of air filters to purify household air, see the fact sheet on
air cleaners (Air cleaners).
What should I do if I suspect a problem?
New pets, cockroaches, water damage, high humidity, and home remodeling can trigger
reactions to indoor allergens. If you suspect that you have allergies, consult your
doctor. Have a skin test to determine the cause of your symptoms. Once the allergen is
identified, take steps to reduce your exposure and control your symptoms.
A professional home inspector or indoor air specialist can help you identify sources of
allergens in your home.
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November 07, 2012