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Published Mar. 15, 2021

The filters in home air purifiers suck in dust, smoke, allergens, and viruses. It pummels them to death and then circulates clean, filtered air. Sounds simple enough, but not all purifiers are created equal, and not everyone is right for every person. Your particular environment is a huge factor in choosing the best air purifier for you. Do you live in a smoggy city? Have there been wildfires?—as is the size of your home. We’ll help you quickly get to know the lingo around air purifiers to make your search easier and more fruitful.

You’ve likely heard of HEPA (high-efficiency particulate air) filters. They are a type of pleated air filter that, according to the Environmental Protection Agency, “can theoretically remove at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles with a size of .3 microns.” The smaller the particle, the more penetrating and nefarious it can be. So when you’re shopping for air purifiers, check out their filters’ MERV (minimum efficiency reporting values) rating. The higher the MERV rating, the better it is at trapping the tiniest particles.

If it’s the coronavirus pandemic that has you shopping for purifiers, it should be said that though a HEPA filter should be able to catch a virus of that size, there’s no conclusive proof that an air purifier can kill airborne COVID-19-carrying air droplets. The Centers for Disease Control and Prevention has stated that any room housing a coronavirus patient “should be exhausted directly to the outside, or be filtered through a high-efficiency particulate air (HEPA) filter directly before recirculation.”

If your main concern about your indoor air quality is lingering food or cigarette smoke odors, make sure the model you’re considering specifically targets fumes and other volatile organic compounds. HEPA filters aren’t good at eliminating odors on their own.

In short, even the best air purifiers aren’t guaranteed to fix all that ails you and your home. But if you’re wondering, are air purifiers really worth it? We think so. The right filter can help distribute cleaner air, and that’s always a good thing.

What to think about before you choose the best air purifiers for you

The best air purifier for you might not be the one your best friend or neighbor loves. You want a HEPA filter with a high MERV rating that’s designed to cover the amount of space you have in your particular room or dwelling. Beyond that, consider whether you want other features like pathogen-killing UV light, smart controls and/or odor elimination. Do you need the best air purifier for pets or perhaps something portable? Air purifiers for mold or models to get rid of smoke? Air filters work only on airborne particles. To get at anything that’s settled into upholstery or rugs, you’ll need a vacuum or other kind of suctioning deep-clean.

Get the best air purifier for the size of your space

There’s an alphabet soup to make sense of when choosing the best air purifier for your home. ACH (air changes per hour) correlates to the airflow of your device. It’s calculated based on the volume of your space, ceiling height, and how many cubic feet per minute the device can cover. It’s independent of other factors, e.g. the efficacy of the filter—to calculate that, you need the CADR (clear air delivery rate) rating; because a HEPA filter is more efficient, its CADR rating may be lower, which is deceptive.

The most important thing to note is that an air purifier’s efficacy cannot be calculated based on square footage alone. You can find handy calculators online to determine the proper purifier for your needs, but here’s what to consider with any device: Will it successfully rid your home of odors with carbon or other comparable filters? Is it a good choice for pet owners? Does it feature UV light? Read the fine print.

Best large-room air purifier: Mila Smart Air Purifier

Smart Controls

This one has a CADR of 447 and responds intuitively to its environment, for example, deep cleaning when rooms are empty and going into a quiet mode when they’re not. Amazon

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This classy, app-controllable large room air purifier adapts to the size of whatever room it’s placed in. It also looks great in any room it’s placed in. The filter has 45 square feet of HEPA, and with 447 CADR, it’s effective in rooms up to 1,000 square feet. Additional features include a sleep mode and white noise, so it won’t interfere with your sleeping habits. The device also features a carbon monoxide detector. It will monitor your room’s humidity and let you know if it detects any mold.

Best small-room air purifier: LEVOIT Air Purifier for Home Bedroom

Works on Odors

This one is ozone-free and has multiple types of filters that together attack 99.97% of smoke, dust, pet dander, pollen, mold, cooking smells and any other particles down to .3 microns. Amazon

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The Levoit promises to help relieve allergies, congestion, and sneezing and is our pick for the best small air purifier. Although we can’t vouch for the unit’s specific efficacy against rhinitis, we can vouch for the fact that it has three filters (one more than most other units): HEPA for dust, pollen, and dander; carbon for odors; and polyester for lint and hair. One fun additional feature is that this one has an aromatherapy option if you’d like a little lavender to help lull you to sleep at night.

The abilities and limitations of a HEPA air purifier

The HEPA filter was initially designed to capture radioactive particles when the atomic bomb was being developed, because it can capture 99.97 percent of particles as small as .3 microns, which can evade other types of filters. (This is sometimes referred to as “true HEPA,” as European HEPA standards are required to trap only 85 percent of particles.) It works by ensnaring, sieving, and rerouting irritating particles.

A HEPA air purifier is considered the gold standard, but it does have limitations. Any particle smaller than .3 microns—for example some viruses and VOCS (volatile organic compounds) like aerosols, ammonia, and other toxins)—will slip right through. Changing your filter often enough is key. A HEPA filter does a great job of capturing mold. If you don’t change the filter, the purifier can end up redistributing that mold back into the air.

Best HEPA Air Purifier: Coway AP-1512HH HEPA Air Purifier

Four-Stage Filtration

This one features the usual pre-filter, HEPA, and odor filtration, plus an additional vital ionizer, which generates an electrochemical reaction to reduce particles in the air. Amazon

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Multiple fan speeds, a timer feature, an air-quality assessor, and a filter-replacement indicator light make this best HEPA air purifier not just quiet and effective, but user-friendly. At just under $200, it’s neither cheap nor exorbitant for an air purifier, and it’s also aesthetically pleasing.

Do air purifiers with UV light really offer extra sanitation?

Opinions on whether air purifiers with UV lights are worth it differ. UV can conquer indoor air particles that escape other filters, like bacteria and viruses, but the EPA has said there’s no way to measure the effectiveness of UV filtration. The UV lights are technically considered pesticidal devices—”an instrument or other machine that is used to destroy, repel, trap or mitigate any pests, including bacteria and viruses”—according to the EPA, and it does not review, and therefore cannot endorse, those. UV light creates potentially harmful ozone, as well, although the amount is small. In our opinion, it’s really too soon to tell if UV light adds anything to an air purifier. We’re not sure we’d go there just yet, but if you’re too curious to wait, we narrowed the field down to the one we would roll the dice on.

Best air purifiers with UV light: Germ Guardian True HEPA Filter Air Purifier

Attacks Airborne Viruses

You get all the benefits of a HEPA filter with VOC capabilities, plus UVC (ultraviolet-C radiation) light, which may be effective at killing viruses that have slipped through the other filter layers. Amazon

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UVC light (the most destructive of all the UVs) in an air purifier works as a UVGI—ultraviolet germicidal irradiation—method of disinfection by attacking the DNA of cells that are floating through the air, like mold spores, viruses, and bacteria. (This means, like all other filters, it cannot do anything for particles that have settled into fabric) The 22-inch purifier filters air four times per hour at maximum speed in rooms up to 153 square feet.

What you should know about air purifiers for allergies

The best air purifiers for allergies depend on what your particular triggers are, because different filters work on different-size particles. Pet hair and pollen are large particles, dust is medium-size, and smoke is small. A combination HEPA-carbon filter is your best bet for filtering the maximum number of irritants.

The addition of an ionizer and UV light, if you’re comfortable with it, adds a belt to your proverbial suspenders. Because UV light does create ozone particles, we recommend choosing an air purifier with UV light that’s approved for sale in California, where ozone-output levels are strictly monitored, like our pick here.

Best air purifiers for allergies: InvisiClean Aura II Air Purifier

Complete Germ Disinfection

Optional ionizer and UV features allow you to add or subtract functionality depending on your particular needs at particular times (e.g. different seasons). Amazon

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The four fan speeds, whisper-quiet operation, and CARB compliance make this air purifier an especially good pick for allergy sufferers. The California Air Resources Board requires purifiers to produce .050 parts per million of ozone or less, so any device with this certification keeps you safe from unsafe levels of the gas.

Related: More tips on dealing with pollen, from an allergist

Need an air purifier for smoke?

Pollutants—like smoke—can aggravate asthma, irritate your eyes, and stress your lungs and heart. An intuitive HEPA purifier with multiple fan speeds, maximum air circulation and zero ozone output is the best one for allergy sufferers and people who are sensitive to smoke. The best air purifiers for smoke have a higher CADR rating. This means your device will be better at eliminating smoke and its odor, whether you’re talking about cigarettes, weed or wildfires.

Best air purifier for smoke: Alen BreatheSmart 75i

Medical-Grade Filtration

This true HEPA tower uses four stages of filtration, long-life filters and zero ozone to remove both fine and large particles and pollutants. Amazon

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Thanks to automatic air-quality detection, when any type of smoke is present, the unit will kick up to turbo. This is an easy pick for the best air purifier for smoke. When no irritants are present, the device goes into energy-saving mode. A CADR rate of 347 (out of 450) makes it especially effective against smoke.

Cheap air purifiers: What you get for under $90

Even cheap air purifiers aren’t that cheap. So chances are, if you’ve found an option that’s within your budget, you don’t need to second-guess it. Go through all the checkboxes you would for a more expensive model: Does it feature a true HEPA filter? Does your air purifier also feature a carbon filter? Is it ozone-free? If the answers are yes, then go for it. What you’re likely sacrificing are bells and whistles you may not even need, like WiFi capability or large-space efficacy, but still possibly getting other extras, like low-noise operation and triple filtration.

Best cheap air purifier: LEVOIT Air Purifier for Home, Core 300

A Lot for a Little

True HEPA, a carbon filter, and a CADR number of 230+ make this a perfectly good pick for individual rooms and small spaces. Amazon

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This cheap air purifier targets smoke, dust and pollen, along with some bacteria and viruses. Specialty replacement filters include a pet-allergy option and a toxin absorber for, particularly smoky or smoggy areas.

FAQs

Q: Should I sleep with the air purifier on?

Sure, there’s no reason not to sleep with the air purifier on! An air purifier contributes to an overall healthy home environment, even while you sleep. In fact, many models feature white noise or overnight modes, so they can continue to work without disturbing you (and possibly even helping you sleep).

Q: Where is the best place to position an air purifier?

The best place to position an air purifier is probably not where you think. Don’t stick it in a corner or behind a piece of furniture to conceal it. Beyond that, if there’s a particular pollutant (smoke, food odor) that you’re trying to combat, place the purifier near it. You want it 3 to 5 feet off the ground—so on a table or sill if it’s not a tower-style—and whenever possible, near sites of good airflow, like doorways and windows. Moving your purifier from place to place helps maximize its efficacy.

Q: Will an air purifier affect my plants?

Your plants should be safe and sound in the presence of an air purifier with one exception: models that expel ozone. Otherwise, purified air is good for plants, just like it’s good for humans.

Ready to buy the best air purifier for you?

In almost every category, the most important quality in the best air purifiers is having a true HEPA filter and a carbon filter. Together, they get you the most coverage in terms of the breadth of pollutants the purifier will attack. Beyond that, the most important qualities are energy efficiency and picking the right model for the size for your room. Everything else—design, whether the device is app-enabled, UV lighting—is just gravy.

Related: How pollution affects the air quality index and your health

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