Air Filters

Air filters in central heating and air-conditioning ducts in your home or in portable room air cleaners help remove indoor pollutants.

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Did you know that the air inside can be more polluted than the air outside? It’s true! Pollen, animal allergens and mold spores can affect the quality of the air inside your home. The U.S. Environmental Protection Agency describes indoor air pollution as one of the top five environmental health risks. For people with allergies, scientific studies have shown that air filtration reduces these airborne allergens and may provide some relief.

Experts recommend two types of filtration:

  • For a single room, look for an air cleaner with a HEPA (high-efficiency particulate air) filter. Check to see that the filter has a CADR (clean air delivery rate) that matches the size of the room where you plan to use it.
  • If your home has a central heating, ventilation and air conditioning (HVAC) system, you can turn it into a “whole house” filtration system by installing a better permanent or disposable air filter. The most cost-efficient choice is a disposable filter with a MERV (minimum efficiency reporting value) rating of 11 to 13 — the higher the MERV rating the better. The filter will catch particles such as pollen, pet allergens and mold, and it won’t impede the airflow. It’s nearly impossible to adequately clean a permanent filter of the tiny particles that cause allergies. In many cases you may replace a permanent filter with a disposable filter that you can throw away when it’s full — typically every three months.

My allergist recommended a good brand of mattress and pillow encasings for my bed, and we've got air filters in the attic, where it’s dusty, and downstairs. I hadn't noticed I had breathing problems around dust, but I'm taking precautions just to make sure.

Buyer Beware

Some air cleaners can actually irritate your allergies, not help them. Ionic electrostatic room cleaners release ions, which force particles to attach to walls or surfaces. But they don’t remove all the particles from the air, and the ozone that is produced is a known irritant.

Inexpensive fiberglass furnace filters have also been shown to be ineffective. Not changing the filter regularly can also do more harm than good.

Many air purifiers designed for home use claim to control allergy symptoms. Unfortunately, there is no scientific data that air purifiers with, for example, ionizers using UV light that supposedly kill bacteria, are effective for allergies.

In the case of pet dander, it’s possible to remove the particles that trigger allergies caused by pets using an air purifier fitted with a HEPA filter. The Environmental Protection Agency (EPA) has said that HEPA filters can remove up to 99.97% of dust, pollen and any airborne particles with a size of 0.3 microns. That means they could help eliminate pet dander found in the air.

For more information, check the EPA’s guidance on indoor air quality in your home.

Other Ways to Improve Air Quality

Using an air filter is just one step toward improving the quality of air inside your home. Here are other things you can do:
  • Keep the humidity level in your home below 50 percent. Do not use vaporizers or humidifiers.
  • Use a vacuum cleaner with a HEPA filter to reduce dust, pet dander and other allergens. Remember, vacuuming temporarily stirs up dust that takes a couple of hours to settle back down.
  • Do not permit smoking in the home at any time.
  • During the height of pollen season, reduce the amount of pollen you’re tracking into the home on your shoes or clothes by either removing your shoes or using a tracking mat at the door.
  • Groom your pet outside your home to cut down on the amount of pet dander in the air. Wash your pet’s bedding regularly.
  • Scrub bathrooms, basements and other tiled areas to cut down on the potential for mold to grow.
Do you still have questions about how air filters can improve your asthma and allergy symptoms? It’s time to speak with an allergist.