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Dust mites, mold, and other things in indoor air can make asthma and allergy symptoms worse. Air filters in central heating and air-conditioning ducts in your home or in portable room air cleaners help remove these indoor pollutants.

My husband smoked only in the living room because it had a portable air cleaner in it. But every time I went into the room, my asthma symptoms got worse, and I could smell the smoke in the rest of our home. The information that came with the air filter claimed that it removed tobacco smoke from a room. My allergist told me that no air filter could remove the smoke. So my husband finally decided it was time to give up smoking.
– Loretta, age 76

Can air filters alone improve indoor air?

No. There are three ways to improve indoor air:

  • Control things such as mold and dust that cause indoor air pollution. This is the best way to improve air quality. For example, reduce clutter in your home, which collects dust.
  • Bring in fresh air and get rid of unhealthy indoor air.
    • Put in a ventilation system
    • Put in ceiling fans and, if possible, design your home so air can move through open windows and doors.
    • Be careful not to bring in outdoor air pollution or pollens if you have pollen allergies.
  • Get rid of indoor pollutants such as dust and pollen
    • Use air filters to trap indoor pollutants. (Most central heating systems, air- conditioning units, and portable room air cleaners use air filters).
    • Clean or replace filters on your air conditioner and furnace every 2 to 3 months.
    • Vent kitchen and bathroom exhaust fans to the outside.

What is asthma?

Asthma is a lung disease that makes it hard to breathe at times. When people with asthma come into contact with something they are allergic or sensitive to, their airways become narrower. That makes it harder for air to get to their lungs.

What is an allergy?

An allergy occurs when you react to things like dust mites or mold that don’t affect most people. If you come into contact with something you are allergic to (called an allergen), you may have symptoms like itchy, watery eyes; runny nose; and sneezing. This is called an allergic reaction.

What kinds of air filters are available?

These air filters can be used in most central heating and air-conditioning ducts and portable room air cleaners.

  • Mechanical filters force air through mesh that traps allergens. The best mechanical filters are:
    • HEPA (High-Efficiency Particulate Air) and ULPA (Ultra-Low Penetration Air). These filters don’t fit in most furnaces but can be attached to a furnace. They also can attach to vacuum cleaners.
    • High-efficiency pleated filters. These filters fit in most furnaces and can be either disposable or washable.
  • Electronic filters use electrical charges to trap pollutants.
  • Hybrid filters contain elements of both mechanical and electronic filters.
  • Gas phase filters remove odors and gases, such as cooking gas, gases given off by paint or building materials and perfume. They can’t remove pollutants such as dust and pollen.
  • Ozone generators, a kind of air cleaner, can be harmful to people with asthma. The ozone from these generators can irritate the lungs. Most experts do not recommend the use of these.

Remember... Getting rid of indoor allergens is the best way to improve air quality in your home.

What else do I need to know about air filters?

  • The quality of filters varies. Talk to your allergist about air filters for your house.
  • Clean or replace filters on your air conditioner and furnace every 2 to 3 months.
  • For air filters to work on your central heating and air conditioning system, the system’s fan must be on.
  • For further information read the Environmental Protection Agency’s (EPA) Guide to Air Cleaners in the Home
  • Filters are available at most hardware stores.

Important... When you’re around someone who’s smoking, the air you breathe contains some of that smoke. This is called secondhand smoke, and it can make asthma and allergies worse and even cause asthma in young children.

No air filter can protect you from secondhand smoke.

Causes of indoor air pollution

  • Tobacco smoke.
  • Mold. It grows in places where there is moisture, such as the kitchen, bathroom, and basement. It can grow on window sills and even in walls, ceilings, or carpet.
  • Dust mites and cockroach allergens, which come from different parts of the cockroach.
  • Fumes from burning oil, coal, or wood.
  • Fumes called volatile organic compounds (VOCs). Certain products like new kitchen cabinets, newly finished floors, new carpet, and paints can give off VOCs.v
  • Radon—a naturally occurring gas you can’t see or smell. It can seep inside from the soil or rock under your home.
  • Carbon monoxide—another gas you can’t see or smell—from furnaces, stoves, and fireplaces that are not vented to the outdoors or not vented correctly.
  • Pollen, pet dander, and outdoor air pollution can enter the home through open windows and doors.

How can I find a high-quality portable room air cleaner?

On the air cleaner, look for:

  • An Underwriters Laboratory (UL) seal, which means the product is safe.
  • A U.S. Food and Drug Administration (FDA) Class II approval notice, which means the product is safe and has a proven medical benefit.

Also ask your allergist for advice.

Do health insurance plans cover the cost of air filters for asthma and allergies?

Probably not. But if the filters have an FDA Class II approval, some of the cost may be covered. Don’t rely on information from the sales person. Check with your health insurance plan. You may be able to (1) use a health savings account (an account that you can put money into to save for future medical expenses) to buy air filters or (2) deduct the costs of an air filter under medical expenses on your taxes.

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