As Covid-19 rages on and winter flu season approaches, air purifiers have become a common sight in people’s homes and offices. But the language surrounding air purifiers can be intimidating, with terms like “HEPA,” “CADR” and “microns” floating around.
We’re here to simplify the value of HEPA filters, CADR tags and air purifiers in general.
Building off our existing guidance on shopping for air purifiers, we consulted medical experts on how air purifiers can clean air. Based on those interviews, new research around the efficacy of air purifiers and our previous coverage, we also highlight highly rated air purifiers worth considering this winter.
SKIP AHEAD Top-rated air purifiers
How to shop for an air purifier
One of the most important features of any air purifier is the high efficiency particulate air, or HEPA, filter, according to experts and various health organizations, including the Centers for Disease Control and Prevention.
HEPA filters aside, manufacturers market their air purifiers with various bells and whistles to address both function and style — though most of them are “gobbledygook,” according to Linsey Marr, a professor of civil and environmental engineering at Virginia Tech. But that doesn’t mean HEPA filters are the only feature to look for, either. Here are the things Dr. Reza Ronaghi, a pulmonologist at UCLA Health in Los Angeles, said you need to consider when shopping for an air purifier.
Filtration: Once you’ve settled on following expert advice and getting an air purifier with a HEPA filter, there aren’t many significant differences among HEPA air purifiers when it comes to air quality. A HEPA filter should filter at least 99.7 percent of particles (including viruses) that are 0.3 microns, which, according to the Environmental Protection Agency, is the particle size that evades filtration most easily. (A micron, also known as a micrometer, is 1,000 times smaller than a millimeter. It’s the standard unit for measuring particles at this scale.)
Flow rate: Knowing the clean air delivery rate, or CADR, in cubic feet is useful. A purifier with a higher CADR will process the air in your room faster, removing particles (including viruses) from the air more quickly. But it may also be more expensive. Marr provided this chart that shows where different models fall on the cost-versus-CADR spectrum.
Room size: Air purifiers can process different volumes of air for different sizes of room, so to make the most efficient choice, keep in mind the size of the room you want to purify. Most models range between 100 square feet and 1,000 square feet. If you want to purify the air in your entire home, you’ll need the correct number of purifiers for your square footage and space them so there are no gaps in the filtration, Ronaghi said. Every air purifier should tell you how large a space it will purify, in square feet.
Top-rated HEPA air purifiers
The CDC recommends anyone shopping for air purifiers look for one that has a HEPA filter and is appropriately sized for the room it will clean. The following air purifiers list features that align with our research and expert interviews and that are highly rated.
This model includes a carbon filter and HEPA filter, according to the company. The brand claims it works in spaces as large as 388 square feet and it comes in Charcoal and Pearl.
This HEPA air purifier can filter out 99.97 percent of particles that measure 0.3 microns, according to Dyson. The company says its filtration tests were conducted in a 2,860-cubic-foot space, which works out to about 350 square feet if you have 8-foot ceilings. It comes in Black and Nickel.
With a HEPA filter, washable metal filters and activated-carbon filters, this purifier can filter out 99.9 percent of particles 0.1 microns or larger from the air, according to Cuisinart, which says it works in spaces as large as 1,000 square feet.
This air purifier has a prefilter, carbon filter and HEPA filter that eliminate 99.97 percent of 0.3-micron particles, according to the company. BISSELL says it works for rooms as large as 308 square feet.
Available for under $100, this air purifier has a HEPA filter that filters out 99.97 percent of 0.3-micron particles, Levoit says, as well as a prefilter and an activated-carbon filter. It works for spaces as large as 129 square feet, Levoit says, and comes with a night light.
This air purifier has four filters: a large prefilter, medium prefilter, carbon filter and HEPA filter. They remove 95 percent of particles 0.1 microns or larger, according to the company. It’s 47 pounds, heavier than most air purifiers, but works for spaces as large as 1,500 square feet, Austin Air says.