How to Shop for an Air Purifier
How does a busy shopper find the right size purifier for a room they want to clean? The US Centers for Disease Control recommends that one should aim for five air exchanges per hour, in a metric known as the ACH. When looking at an air purifier, look at the cubic feet per minute in airflow at the lowest setting. When measuring the cubic footage of your room, you need the area of the room times the height. Imagine a one-foot cube of styrofoam. How many cubes could you fit into a room?
Anyone shopping for an air purifier also needs to look for two acronyms and terms. First, look for CARB certification, which means that the air purifier passed the rigorous standards of the California Air Resources Board. Next, check the filter type. Below, we break down the differences. Also, don’t forget to unwrap your filter! There’s a special kind of horror that comes with realizing you’ve been running your air purifier with a plastic-wrapped HEPA filter.
HEPA Filters: This is a high-efficiency particulate air filter that can remove at least 99.97 percent of dust, mold, pollen, bacteria, and airborne particles as small as 0.3 microns. It’s a great option for those who suffer from allergies or respiratory issues, since it can help to clear out airborne particles that can trigger symptoms—like sneezing, sore throat, difficulty breathing, coughing, and more. It’s worth noting, however, that HEPA filters don’t remove volatile organic compounds from the air the way activated carbon filters do. But these are typically paired with carbon filters.
Activated Carbon: Activated carbon filters (also known as activated charcoal) are highly effective because they are very porous and have a large surface area—allowing the filters to absorb gas pollutants, odors, and VOCs. They’re best for removing fumes, smoke, and chemicals from the air. But these filters have to be replaced more often depending on the environment. For example, if there’s a wildfire in your area and the air purifier is working more intensely than usual, it’s important to replace a saturated filter to avoid toxic gases from being released back into the air.
Washable Air Filters: A few of the air purifiers we’ve listed in this guide come with washable prefilters in addition to a HEPA and/or activated carbon filter—which is what you’ll typically find. These are the most cost-effective since you don’t have to buy new ones each time you need to replace a filter. Simply remove it, scrub it with soap and water, and let it dry.
UV-C Sanitizer Filters: Ultraviolet filters use UV light to kill viruses, parasites, mold spores, and bacteria. They can’t remove airborne particles, VOCs, or gas pollutants, so they’re only fully effective when combined with a HEPA filter. According to the United States Environmental Protection Agency, UV lights without proper lamp coatings have the potential to emit ozone. We recommend checking this list from the Association of Home Appliance Manufacturers for air purifiers that have been shown to emit little to no ozone.
How to Check Your Air Quality
Many large states and cities are required to report the local outdoor Air Quality Index, which was established by the EPA and measures the concentrations of major air pollutants, like ground ozone and carbon monoxide, that are regulated by the Clean Air Act. We like AirCare (iOS, Android), but your state or county may have even more localized apps.
To check if your indoor air quality stacks up, consumer monitors like the Temtop M10 ($90) and Airthings View Plus ($300) also measure carbon dioxide, temperature, and humidity, in addition to pollutants and particulate matter. The M10 measures formaldehyde too, a noxious chemical that off-gases from common household items, such as particleboard furniture and some foam mattresses. Need more information? Check out our complete guide to checking your air quality.
Air Purifiers We Don’t Recommend
Ikea Starkvind for $150: Ikea’s Starkvind air purifier hit the American market in 2021. It’s stylish and relatively inexpensive and has the option to add on a carbon filter for gases such as benzene. It can be purchased either on its own or built into a wooden side table, but it’s worth noting that the Starkind took me an hour to assemble. While it is CARB-certified, meaning it passed the rigorous standards of the California Air Resources Board, it does not have a HEPA filter. Thinking I had an early version made for media, I went to my local Ikea. I bought a Förnuftig, and its manual listed the filter as HEPA. It’s not. We reached out to the company; at the time of publication, Ikea said it was still routing the question to the appropriate team. The question remains: If you’re buying an air purifier, why not buy a HEPA? —Lisa Wood Shapiro
Dyson Purifier Humidify+Cool Formeldahyde for $1,000: Dyson’s Humidify+Cool Formaldehyde reminds me of those 3-in-1 appliances that are an amalgam of a toaster, coffee maker, and egg cooker all in one. But if you’re going for an air purifier that removes gases, then I would opt for one that removes formaldehyde, a known carcinogen. My review unit was never able to oscillate, but it’s supposed to. (I tried troubleshooting through the manual, but the more features that an item has, the more that can go wrong.) It also has a two-year warranty, which seems short. —Lisa Wood Shapiro
Morento Air Purifier for $100: This CARB-certified purifier caught our attention earlier this year for its value. With a CADR of 200 cubic feet per minute, the Morento is not only more powerful than most other purifiers at its price point, it’s got all the features of higher-end models, including a PM 2.5 sensor and ring-light indicator, plus smart capability through the Havaworks app. During the testing period, however, the fan never increased speed to compensate for higher PM 2.5 levels, even when I burned incense in the room to raise the level into the 500s. This persisted despite the machine being set to auto mode both in the app and on the machine itself, plus my cleaning the sensor and resetting the unit by unplugging it. Regardless, even if this feature had been working properly, the Morento gives a strangely wide margin for acceptable PM 2.5 levels—the ring light indicator continued to glow green (“good”) up to 75 PM 2.5, which is 15 times more than the World Health Organization–recommended level of 5 micrograms per cubic meter. —Kat Merck
