Air Filter for Allergies

Yes, an air purifier with a HEPA- or ULPA-rated filter is effective at removing allergens from the air. Studies have shown that trapping and removing allergens such as pet dander and pollen from the air with an air purifier can reduce allergic responses.⁶

In moist environments and if not regularly maintained, air filters in HVAC systems have actually been found to support mold growth. This happens if moisture condenses on the filter media as air passes through. The biological material trapped by the filter can serve as an excellent source of food for the mold. When the mold grows from the upstream to downstream side of the filter, mold spores can be released into the air coming from the filter, possibly worsening allergies. A properly maintained air filter should not cause or worsen allergies.

There may be a link between food allergies and asthma attacks in children. However, it is not clear if the link is causal. It is possible that increased allergic responses present as both food allergies and asthma, and that an allergic reaction to food may precipitate an asthmatic episode. Whether this link runs in both directions is unclear, so it cannot be said for certain if an air filter will or will not help alleviate food allergies.

The best filter for allergies depends on a number of factors. If you are allergic to solid air contaminants like pollen or mold, a HEPA or ULPA filter can be very effective at reducing airborne allergens. All air filters for allergies need to be the correct size for the space they are meant to treat. Effective air purification relies on being able to process pollutants out of the air faster than they can be regenerated or introduced. When an air filter for a room is too small for the room it is used in, the filtering system may not be able to effectively clear the air of allergens.

Pet dander, pollen, and mold are all large enough to be trapped in HEPA and ULPA air filters. There is a chance that a very small fraction of these irritants will make it through the filtration media. HEPA filters remove 99.97% of particulate 0.3 microns in diameter, and are actually more effective at removing larger particles. Pollen, mold, and pet dander are all larger than 0.3 microns, so less than one in three thousand of these allergens make it through the filter. ULPA filters remove even more particles; less than one in 100,000 will make it through.