In a world more attuned than ever to what our air transmits, buying and using an air purifier makes more sense than ever — especially if someone in your household has asthma or faces other health challenges. From filtering aerosol droplets (which can carry COVID-19 virions) to pollen to wildfire smoke out of the air you breathe, air cleaning devices can dramatically improve the quality of air in your home. But with the overwhelming number of air-cleaning devices on the market, all advertising various filtration methods, how do you find the best one?

I’ve extensively researched the field of products, tested the extra features on a dozen of the most popular models, interviewed various experts in the field of indoor air quality and written up the definitive list of the best air cleaners around. Ready to buy an air purifier? Look no further.

Before the recommendations…

Before getting into the details of which devices are best and why, it’s important to understand the basic mechanisms that these products use to clean your air. To get a handle on these methods, I talked to Richard Shaughnessy, director of Indoor Air Research at the University of Tulsa.

According to Shaughnessy, who has a doctorate in chemical engineering, most air cleaners run your air through a filter designed to catch particles you might otherwise inhale. These are usually High Efficiency Particulate Absorbing filters and they’re designed to capture 99.97% of particles sized 0.3 micron or larger. HEPA filters reliably remove smoke (including from wildfires), pollen, dust and other particulate matter that pollutes home environments.

Activated carbon offers another type of filter, which captures odors and gaseous pollutants that can slip through a HEPA filter. “[Carbon filters are] good … to an extent,” said Shaughnessy, “but they need to have a sufficient amount of carbon. You don’t want breakthrough happening where the carbon becomes fully saturated and it releases what was captured back into the air.”

According to multiple researchers I talked to, most consumer air purifiers simply don’t have enough activated carbon to be an effective odor filter for more than a short period of time.

Read more: Will air purifiers protect you from COVID-19, wildfire smoke and pollen?

Another common type of air cleaning works via ionic filtering. These filters can be effective, according to Shaughnessy, but they have a number of shortcomings: Some don’t actually remove particulate from the home, but rather cause them to attach themselves to surfaces around the home. Others must be cleaned consistently, or they might begin to emit ozone — itself a pollutant.

While some ionic purifiers are effective and standards for them have risen significantly in recent years, the benefits an ionic purifier offers over a HEPA filter are in many cases negligible — particularly given the risk they occasionally pose.

An important standard to keep an eye out for is the AHAM Verified Clean Air Delivery Rate, which tells you how much air a purifier can process in a given time frame. Not every company uses this standard, but most do.

Recommendations get a little more complicated when companies don’t list a CADR, or when they employ proprietary filtration methods.

Some major players, like Dyson and Molekule, offer their own standards. That doesn’t necessarily mean that their devices are inferior, but rather that they require extra scrutiny. In these cases, I looked at the explanations presented by the companies themselves and talked to third-party specialists. By and large, such devices — even if they do accomplish what they claim — still end up overpriced compared with competing products with more readily accessible evidence backing up their claims.

For the recommendations below, I primarily consider the power for the price (that is, the higher the CADR and the lower the price, the better). Secondarily, I look at additional cleaning modes, the helpfulness of controls, the general design and the noise level. The perfect air cleaner looks sleek enough to fit into most modern decor, can operate as desired with minimal fiddling and can thoroughly and quietly clean your air.

The rest of the field

The air purifiers above are only three of the 12 devices I tested. Other HEPA cleaners, like the $100 Levoit Core 300, the $160 Winix 5500-2, the $90 Bissell and the $85 GermGuardian all offer only so-so power for their prices. All four of those models offer carbon or charcoal filters for removing odors and gaseous pollutants, but the filters in all of them contain only a few ounces of the medium, meaning they won’t last long with use.

The IQ HealthPro Plus wasn’t among the devices I tested, in part because I was looking at more affordable options. But IQ’s $900 air cleaner is one of the few devices on the market to contain multiple kilograms of activated carbon, which will filter out odors and gaseous pollutants much more effectively than most consumer air cleaners under $1,000, according to specialists I talked to.

Two devices I tested featured ionic filters: the $184 Coway AP-1512HH I mentioned above and the $230 Sharp FPK50UW. Sharp’s CADR rating is only 259 square feet, which is significantly lower than Coway’s and not great for the price.

The Partu ($50) and Holmes ($38) air purifiers were the most affordable devices I tested and they both offer HEPA filtering for small rooms. I could see someone using them on a desk in an office, for instance, to great effect. But both felt a little cheap and neither gave an official CADR, so I would recommend saving up for something a little more reliable if cleaner air is a high priority.

I generally found more expensive models to have some of the hardest-to-verify claims. Dyson’s $550 TP04, for instance, uses a HEPA filter, but provides no CADR. A Dyson spokesperson told me, “CADR as measured by some current methods is not an accurate representation of a real home,” and thus the company has developed its own testing procedures “to replicate a more realistic setting.” That includes a testing room that has over double the footprint of AHAM’s testing rooms, along with nine sensors placed around the space (versus AHAM’s single sensor). The Dyson TP04, perhaps unsurprisingly, performs well according to Dyson’s own metrics.

In addition, the TP04 features a handful of extra goodies, including an oscillating fan to help circulate clean air around larger rooms, an app with home air quality data and a small-but-nifty display. But is all that worth the $300 price bump from, say, Honeywell‘s Home purifier?

For most people, the answer is likely no — especially considering that Dyson’s device hasn’t stacked up especially well against the competition in third-party testing, such as Wirecutter’s, where its performance was in line with the far more affordable Blueair 411. What’s more, Dyson doesn’t give a guideline for the size of room in which you should use it, which makes it harder for customers to understand whether it’s the right device for their particular needs.

At the end of the day, we can set aside any smaller frustrations with clarity or branding for a simple reason: Devices like the Honeywell Home use the same fundamental filtration technology — with well-documented results — to clean the air in large spaces for about half the price of the Pure Cool ($520 at Amazon). Unless you love the aesthetic, Dyson’s air purifier isn’t worth the money.

What about Molekule?

You may have heard of another air purifier called Molekule, made by a company of the same name, which grabbed headlines for its attractive design and proprietary filtration technology back in 2017 — and is even, strangely enough, sold at the Museum of Modern Art in New York. What about that?

The Molekule presents a complicated problem: Its maker claims its proprietary PECO filter destroys particles much smaller than 0.03 micrometers, but it filters air at such a slow rate that, even if the company’s claims are accurate, it cleans the air very inefficiently compared with HEPA models (as Consumer Reports rightly pointed out in its highly critical review late last year).

On the other hand, the Lawrence Berkeley National Laboratory, one of the premiere indoor air research centers in the country, recently released a government-funded study showing that the PECO effectively filters out volatile organic compounds — that is, compounds that can easily become gaseous pollutants in the air, which HEPA filters do not capture. Reviewers at Consumer Reports and the New York Times’ Wirecutter, which called the Molekule’s larger model “the worst air purifier we’ve ever tested” and the Air Mini “the second-worst,” didn’t appear to test VOC reduction.

We can’t recommend the Molekule Air Mini Plus, which I tested, as a result of these problems coupled with a recent decision by the National Advertising Review Board to force a retraction of many of Molekule’s misleading advertising claims. That said, the air purifier does appear to address a problem that most HEPA-reliant cleaners simply don’t: the presence of gaseous pollutants in the home. Such pollutants have plenty of sources, whether from paint, furniture, cleaning solutions or even some composite boards. For that reason alone, Molekule’s eye-catching brand is worth keeping tabs on — especially as its latest air cleaner was just approved by the FDA as a Class II medical device.

Do you even need an air purifier?

Given the rise of COVID-19 over the past few months, you may be thinking about air purifiers in a fresh light. In home settings though, transmission usually occurs through close contact, which means an air purifier probably won’t protect you if a roommate or family member in the same house gets sick. Purifiers may help businesses and restaurants trying to improve the air in their indoor spaces.

Beyond COVID concerns, in home settings, air purifiers don’t offer much value to the average consumer. According to microbiologist and Vice President of Scientific Communications at the American Council on Science and Health Alex Berezow, “Unless you have some sort of medical condition (asthma, allergies), I just don’t think an air purifier is worth the money.”

Human lungs, Berezow pointed out in a recent blog post, filter the air we breathe sufficiently — especially in places like most parts of the United States, where air is fairly consistently clean.

On the other hand, for households with an asthmatic or otherwise immunocompromised child, air purifiers have significant benefits, according to Berezow and Dr. Elizabeth Matsui, a professor of population health and pediatrics at the University of Texas, Austin’s Dell Medical School.

Matsui has extensively researched the effects of air purifiers on children with asthma and says the devices can make a big difference — though they’re no substitute for well-ventilated and smoke-free homes or proper medical care. Furthermore, there is no evidence to suggest that air purifiers diminish the chance of children developing asthma.

In short, air purifiers are popular for a reason: They mostly do what they say, cleaning the air inside your home. And depending on your health needs, or if you live in a home with many sources of pollution, cleaner air might really make a big difference for you or your children. If you think the benefits of an air purifier might help someone in your own home, it’s always worth talking to an allergist. If you’d rather just grab an air cleaner and call it a day, you can’t go wrong with the recommendations above.

Still have more questions about air purifiers and whether you’re ready to buy one? Check out our air purifier FAQ for more info.

Correction, July 13: A previous version of this article incorrectly described the Blueair 411’s features. The Blueair 411 has a “change filter” indicator, and is AHAM-certified for a 161-square-foot room.