Can Air Purifiers Help?

The best ways to improve indoor air are to remove the pollutant sources and ventilate with clean outdoor air. Room air purifiers can help when those methods are insufficient or not possible. Room air purifiers are designed to filter the air in a single room, not the entire house, like a whole house system tied into the home’s heating, ventilating, and air conditioning system. And while they do help to reduce indoor pollution, there are limits to what they can do.

What Air Purifiers Do Well
The air purifiers that do well in our tests proved in our labs to be good at filtering dust, smoke, and pollen from the air. Multiple studies of room air purifiers show that using HEPA filters results in reductions of 50 percent or higher in particulate matter. In one 2018 study of about 130 households, filtration resulted in about 30 percent reduction in coarse particles, like dust.

air purifier factory

But how does that affect health? Almost a dozen studies—including ones conducted in Vancouver, British Columbia; Taipei, Taiwan; and Massachusetts—looked at cardiovascular effects and showed improved cardiovascular health among participants. The EPA’s review of eight studies focused on allergy and asthma symptoms, and showed modest improvements in at least one health area, such as some allergy symptoms (which vary from person to person). And asthmatic participants in a 2018 study by the University of California, Davis (PDF) reported a 20 percent reduction in clinic visits.

Still, the scientific and medical communities can’t definitively link the use of air purifiers to health benefits because reported health benefits are inconsistent among participants and there have been very few long-term studies. Plus, some studies had other variables at play, such as the regular use of a vacuum cleaner (CR can help you choose one of those, too), pillow covers, and the removal of pets from the bedroom, all of which can affect results.

As for the coronavirus, air purifiers with HEPA filters are capable of capturing the droplets that the coronavirus travels in (when people cough, talk, or breathe). But you’ll need one that consistently draws in enough air to reduce virus particles.

What Air Purifiers Don’t Do
An air purifier can remove allergens only while they’re floating in the air. Larger, heavier allergens, such as mites, mold, and pollen, settle to the ground so quickly that the air purifier can’t capture them in time.

What We Don’t Yet Know
Radon is another blind spot for air purifiers and other air cleaners, according to the EPA; studies are inconclusive on air purifiers’ ability to tackle this dangerous gas. And in fact, there is insufficient research on air purifiers that address gaseous pollutants as a group, so it’s unclear how effective air purifiers are. There is also limited data on the effect of ionizer air purifiers on health. That brings us to another important consideration: the various kinds of air purifier technology available.