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Air: Indoor Allergens

Indoor allergens are biological or chemical substances that trigger the immune system, causing an allergic reaction.

Biological sources of allergens include:

  • Bacteria
  • Dust mites
  • Insects
  • Mold
  • Pets
  • Plants

Chemical sources of allergens are often gases or particles released by items such as:

  • Building materials
  • Dyes
  • Fabrics
  • Glues
  • Paints
  • Perfumes
  • Solvents

How can I be exposed to indoor allergens?

All buildings contain indoor allergens. Most people are exposed to these allergens by breathing them in. Exposure can also happen if allergens are ingested or if they come in contact with the eyes or skin.

Indoor allergens come from many different sources. For instance, outdoor plants release pollen that can enter buildings, triggering hay fever as an allergic response in some people. Also, metals, perfumes, dyes, and solvents found in common household products—such as carpet, upholstery, laundry detergent, and paint—can cause allergic reactions.

What happens if I’m exposed to indoor allergens?

If you’re sensitive to a particular allergen and you come in contact with it, it can cause an allergic reaction, such as:

  • A runny nose.
  • Coughing.
  • Skin rashes.
  • Sneezing.
  • Trouble breathing.
  • Watery eyes.

Severe allergic reactions can require immediate medical treatment.

How sensitive you are to an allergen varies. For instance, some people are allergic to cats, while others aren’t. If you’re allergic to cats and are also exposed to a chemical, like tobacco smoke, it can make your symptoms worse. How long you’re exposed to allergens can affect the severity of your reaction, too.

How can I reduce exposure to indoor allergens?

There are a few things you can do to reduce exposure to indoor allergens. They include:

  • Find out which allergens affect you by talking to your doctor. After you identify the source, remove it to prevent future allergic reactions.
  • Keep your home clean of mold, cockroaches, and dust. Keep areas dry and clean, such as bathroom windowsills, basements, and refrigerator doors.
  • Keep the relative humidity level in your home between 30% and 50%. This helps control the growth of dust mites and mold.
  • Vacuum regularly to get rid of allergens in dust. Use special vacuum bags (those with a high-efficiency particulate air (HEPA) filter) to control small dust particles and prevent them from re-circulating back into rooms.
  • Wash bed sheets in hot water every seven to 10 days to kill dust mites. Sealed mattress covers can help keep dust mites from getting inside mattresses.
  • If you’re 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 help reduce exposure to chemical allergens.
  • Simple window coverings and hard-surfaced floors make it easier to control dust levels in your home. Clean machine-washable throw rugs frequently to remove dust and other allergens.
  • Use fiber-filled pillows instead of feather-filled pillows.
  • Watch out for food allergies, which can increase sensitivity to indoor allergens.

To learn how air filters can help purify indoor air, visit our Home Air Cleaners webpage.

What should I do if I suspect a problem?

A new pet, water damage, high humidity, and home remodeling can all trigger reactions to indoor allergens. If you suspect you have allergies, talk to your doctor. They may recommend a skin test to determine the cause of your symptoms. Once you’ve identified an allergen you’re sensitive to, you can take steps to reduce your exposure.

A professional home inspector or indoor air specialist can help you identify allergen sources in your home.

Last revised January 3, 2023