Do Air Purifiers Work? Yes—Now Let’s Clear the Air on Some Misconceptions

Including whether they help reduce wildfire smoke and allergens

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Whether the recent wildfires have you concerned about the air quality in your area, you've been combatting allergies or you're just into the idea of breathing fresh air (uh, who isn't?), you may be considering getting an air purifier. But deep down, you can’t help but wonder: Do air purifiers work?

They promise to filter out dust, pollen, smoke, even germs—but do they really deliver on that, or are they just overpriced fans? We pored over research and turned to the EPA, as well as Dr. Tania Elliott, who's dual board-certified in allergy/immunology and internal medicine for answers.


Meet the Expert

Dr. Tania Elliott, an allergist and national spokesperson for the American College of Allergy, Asthma and Immunology. She also serves as a clinical instructor at NYU Langone Health and is the Chief Medical Officer at Ascension, a non-profit healthcare company.

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What Do Air Filters Actually Filter Out?

Air purifiers (also known as air sanitizers or portable air cleaners) suck particles from the air, such as pollen, fungal spores, dust, pet dander, soot, bacteria and allergens. So, how do they work? The machines use a filter—or a combination of filters and UV light—to remove impurities and pollutants from the air. They’re designed to improve the air quality in a single room.

Do Air Purifiers Work?

Yes—to an extent. As the Environmental Protection Agency (EPA) notes, while they are effective at cleaning the air and reducing air pollution, they cannot remove all pollutants.

OK, So *How* Do Air Purifiers Work?

In general, air purifiers filter in one of two ways: via fibrous media air filters or electronic air cleaners. The former is kind of like a catcher’s mitt, with the particles getting scooped up in the filter. The latter—electronic air cleaners, which include electrostatic precipitators and ionizers—use electricity to charge particles and adhere them to oppositely charged plates in the machine. Some even use ultraviolet light to kill airborne microorganisms. Now, don’t you feel all Bill Nye for knowing that?

Can Air Purifiers Help with Wildfire Smoke?

Yes. The EPA recommends using a portable air cleaner and/or high-efficiency HVAC filter when the air quality is poor in your area due to wildfire smoke, with the caveat that it should be the right size for your room (more on that below) and should not produce ozone. You'll also want to make sure it can filter out particles 2.5 micometers or smaller, like the models suggested at the end of this story.

If you're in a bind or cannot afford an air purifier, the EPA also offers a tutorial on creating a DIY one using an air filter, a box fan and duct tape or bungee cords. (Though they also say this should not be a permanent solution, and there are concerns that the fan could overheat, posing a safety hazard, so if you pursue this option, please keep an eye on it.)

Will an Air Purifier Protect Me Against COVID-19 and Other Illnesses?

The EPA and many doctors agree that air purifiers are helpful—especially if the outdoor pollution is high, or if it’s too cold to throw open your windows and let in tons of fresh air. “Viral droplets, like SarsCoV2 and the flu, these can stay suspended in the air for hours, so an air filter can't hurt, but remember the droplets can also land on surfaces and sit there as well,” explains Dr. Elliott. “An air purifier shouldn't replace mask-wearing, hand washing, isolation, not sharing personal products and sanitizing measures.” As the CDC says, consider ventilation part of a “layered strategy” to prevent the spread of the coronavirus.

Do Air Purifiers Really Help People with Allergies?

Yes—and they can be particularly helpful for people who suffer from pollen or pet-related allergies. “Pet allergens stay suspended in the air for months at a time, even if the pet is no longer in the home,” explains Dr. Elliott. “Air purifiers that can capture fine particulate matter are your best bet. It is also helpful for people with pollen allergy, as we inevitably track pollen into the home from our clothes, shoes and hair.” By “fine particulate matter,” she means dust, pollen, mold and the like. Particles considered “fine” are less than 10 microns in diameter (ultrafine ones, such as soot, smog and viruses, are less than 2.5). For comparison, a human hair is about 50 to 70 microns in diameter. So we’re talking small—really, really small.

Unfortunately, air purifiers “won't work for people with dust mite allergies, as dust mites are too large of a particle to remain airborne,” Dr. Elliott says. For that type of allergy, your best bet is to vacuum, dust and wash your bedding regularly, and invest in allergen-proof bed covers.

Still, many HEPA filters and air purifiers tout being able to remove particles 0.3 microns in diameter. Keep an eye out for those if you’re looking for a model that can help remove viruses or smoke particles from the air (the EPA recommends models that remove particles less than 1 micron in diameter). With that in mind, we rounded up four top-reviewed ones that all meet the criteria below.

What Should I Look for in an Air Purifier?

1. CADR (Clean-Air Delivery Rate) Rating

The Clean Air Delivery Rate (CADR) is a number you’ll find on most air purifiers’ packaging—or at least any company that voluntarily submits their machine to the Association of Home Appliance Manufacturers (AHAM). The CADR indicates the amount of clean air a purifier can produce at its highest fan speed. If the unit can successfully filter tobacco smoke, dust and pollen particles at a certain rate, the manufacturer will (typically) submit the purifier for AHAM verification.

2. AHAM (Association Of Home Appliance Manufacturers) Verified Mark

The AHAM is an organization that verifies a purifier's CADR rating through independent laboratory testing. “During testing, the air cleaners are exposed to specific quantities of tobacco smoke, dust and pollen. After the air cleaner is operated for a certain duration, the amount of each pollutant in the air is measured,” according to the official AHAM website. “The higher the CADR, the greater its ability to filter that specific pollutant. Air cleaners with HEPA filters are designed to remove 99.7 percent of airborne pollutants [that are] .3 microns and larger.” Long story short? An AHAM certification is a quick way to know the device can effectively remove smoke, dust and pollen from your home.

3. True HEPA

“High-efficiency particulate air” (HEPA) is another verification for filters defined by the U.S Department of Energy. Basically, it means that the filter can remove at least 99.97 percent of dust, pollen, mold, bacteria and any airborne particles with a size of 0.3 microns. However, it’s important to keep in mind that “there is no widely accepted definition of HEPA performance in consumer products,” according to the EPA. “They are unlikely to be equivalent in performance to HEPA-designated filter systems used in health care buildings and industrial processes, but still have very high removal efficiency (i.e., usually 99 percent or higher) for the reported particle sizes tested.”

4. Size Guidelines

“Be sure to get one that matches the size of the room by checking the CADR,” says Dr. Elliott. There’s one CADR score for pollen, one for dust and one for smoke, and the association recommends choosing a purifier with a CADR score that’s at least two-thirds of the room’s area. We know—it sounds complicated. But really, it’s just basic math: If you’re clearing the air in a 10-foot by 10-foot room, that’s 100 square feet, so you want a CADR score of at least 67 in each of those three categories.

Are There Any Types of Air Purifiers I Should Avoid?

Yes. Stay away from ozone-generating air cleaners. As the name implies, they produce ozone, which can cause health issues in high concentrations, and the EPA reports that ozone does little to actually remove pollutants. On that note, it’s worth mentioning that no federal government agency has approved of their use in homes (though some brands may claim that). You’re better off going with an air purifier that uses a fibrous media air filter or an electric air cleaner.

So What Are the Best Air Purifiers I Should Check Out?

air purifier 1 sq
  • Pros: automatically senses air pollution issues, syncs with Dyson Link app to provide reports, does triple-duty as a fan, heater and air purifier
  • Cons: pricey, somewhat noisy
  • Does It Capture Ultrafine Particles (2.5 PM or less)? Yes—it "captures 99.97 percent of allergens as small as 0.3 microns," per the brand

This model can replace your space heater and fan, and it oscillates 350 degrees to spread that fresh air around the room. While it is an investment, reviewers rave about how easy it is to use and how powerful it is, sending out 77 gallons of purified air per second.

Most Affordable

2. Levoit Air Purifier


  • Pros: quiet, easy to use, compact size
  • Cons: replacing filters can get costly
  • Does It Capture Ultrafine Particles (2.5 PM or less)? Yes, the H13 True HEPA Filter captures 99.7% of particles, down to 0.3 microns

Ideal for 403-square-foot-or-smaller spaces, this compact air purifier is powerful, yet affordable. Reviewers say it's been great at combatting everything from dusty rooms to removing the scent of wafting smoke from chain-smoking neighbors.

Most Discreet Air Purifier

3. Dupray Bloom Air Purifier


  • Pros: covers 1,517 square feet, making it ideal for large spaces; can be used as a planter or side table; sleek look
  • Cons: highest power setting can be noisy, some reviewers say the auto-detect feature isn't very sensitive
  • Does It Capture Ultrafine Particles (2.5 PM or less)? Yes—it captures 99.7% of particles and odors, per the brand

Air purifiers can be an eyesore, but not this baby. It doubles as a planter or accent table, and you can choose one of 13 accent colors for the purifier pre-filter (for an extra $20), so it matches your decor. But what really makes it worthwhile is its top-notch HEPA-13 filter, which features three-stage filtration.

Most Portable Air Purifier

4. LG PuriCare Mini


  • Pros: great for traveling, lightweight, long battery life
  • Cons: not suitable for larger spaces, like living rooms and open floor plans
  • Does It Capture Ultrafine Particles (2.5 PM or less)? Yes—its four-step air filtration system detects and removes 99 percent particulates as small as 0.3 microns

If you'd want to purify the air in a home office, nursery or other small space, the LG Puricare Mini will be your go-to. Even more so if you travel—or want to clear the air in your car. It's roughly the size of a water bottle, making it ultra-transportable.

  • Pros: very quiet, good for spaces up to 361 square feet, offers real-time air quality monitoring
  • Cons: somewhat bulky
  • Does It Capture Ultrafine Particles (2.5 PM or less)? Yes. According to the brand, it captures—you guessed it—99.7% of particles, including ones less than 0.3 microns

Several reviewers with allergies say they sleep easier with this machine running, which features one-, four- and eight-hour timers so you don't have to continually turn it on and off. In addition to its three-stage filtration system, this Coway model also features a filter replacement light, so you can see at a glance when it's time to swap yours out.

How Long Does an Air Purifier Take to Clear the Air in a Room?

The short answer? Give it at least 30 minutes to an hour. Some companies recommend running it all day, every day, since pollutants are continually being tracked into the house and are wafting through open windows. (Of course, it’s worth noting the impact that doing so may have on your electricity costs.)

What's the Best Place to Put an Air Purifier?

Let’s be real: Air purifiers aren’t the chicest-looking additions to your decor, so it’s tempting to tuck them behind a plant or large piece of furniture. Don’t. You want to keep them in the room where you spend the most time—ideally, the room where the most vulnerable in your family (infants, elders and people with asthma) spend the most time—and in a position so that the clean air is close enough so they’ll be able to breathe it in, according to the EPA. Beyond that, it’s also worth consulting the manufacturer’s instructions for placement.

What Are Other Ways I Can Improve the Air Quality in My Home?

1. Vacuum Often

“A clean house may be a healthier house, because good indoor hygiene can greatly cut down on dust and animal dander,” says Dr. BuSaba. “Your cleaning efforts should focus on strategies to reduce the accumulation of pet dander, mold and dust lurking in your home.” Be sure to vacuum carpets and area rugs at least once or twice a week with a vacuum cleaner equipped with a HEPA filter for best results.

2. Regularly Change Air Filters

If you have a forced-air heating system, you’ll want to make sure you’re changing the air filters every three months, according to the CDC. “In homes where the HVAC fan operation can be controlled by a thermostat, set the fan to the ‘on’ position instead of ‘auto’ when you have visitors. This allows the fan to run continuously, even if heating or air conditioning is not on,” adds the National Center for Immunization and Respiratory Diseases (NCIRD).


Editor's Note: This article originally ran in January 2021. It has since been updated and expanded in light of the wildfires in Canada, which have caused air quality issues in the region, as well as the Eastern United States.

Why You Should Trust Us

Candace Davison is PureWow’s vice president of editorial, overseeing food, home and major franchises, like the PureWow100 review series and the Happy Kid Awards. She’s covered all things lifestyle in her 10+ years of digital media experience, though she has a weakness for baking (she has *opinions* on stand mixers), DIY-ing and gadgets, all of which she shares on PureWow and her social media accounts. Davison has published multiple cookbooks, and her work has appeared in O, The Oprah Magazine, House Beautiful, Good Housekeeping, Cosmo, Esquire and Delish, among other publications.

Sydney Meister is PureWow’s Assistant Home + Lifestyle Editor. Along with covering the latest interior design trends, she writes about everything from dating and relationships to weddings, travel, real estate and must-have beauty products. Before PureWow, Sydney spent eight years working with various interior designers across NYC—primarily as a content creator focusing on trend forecasting and reporting. She's a go-to resource when it comes to interior styling tips and decor recs to keep your home looking au courant (hint: it's time to ditch the modern farmhouse look). Find her on Instagram for the lastest dating and decor updates.

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Candace Davison

VP of editorial, recipe developer, kitsch-lover

Candace Davison oversees PureWow's food and home content, as well as its franchises, like the PureWow100 review series and the Happy Kid Awards. She’s covered all things lifestyle...
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Sydney Meister

Assistant Editor

Sydney Meister is PureWow's Assistant Editor, covering everything from dating trends and relationship advice (here's looking at you, 'soonicorns') to interior design, real estate...
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