Pre-filters: A screen housed within an air purifier that traps larger air pollutants—like dust or pet dander—can be another helpful add-on to your device. Called a pre-filter, it’s an added layer of protection that catches all the big stuff so your HEPA filter can carry on doing its best work without getting clogged. It’s also usually made of a material that’s easily washable, so you don’t have to constantly replace it.
Carbon filters: Carbon filters are a third type of screen that’s apt at trapping odors from volatile organic compounds, or VOCs, along with the strong scent of your weed or the wet dog who just traipsed in from outside. They work through a process called adsorption that uses activated carbon to attracts contaminants to attach to the outside of the filter.
Coverage: Air purifiers are broken down by “coverage” or the largest room they can effectively clean, typically circulating the air two to five times per hour. This ranges from small kitchens to large family rooms, so break out the tape measure. In general, it’s better to have several small air purifiers in multiple rooms, rather than one large one for the entire house, as Nimmagadda notes that even with a device equipped to cover a larger area, it’s going to take a lot longer to purify the air in a bigger space.
Where should I place my air purifier?
“You can’t put a small HEPA filter in the corner of the room expected to protect you when you’re on the other side of the room,” says Nimmagadda. For best results, place it in the room you spend the most time in, like your bedroom, and make sure it can circulate air effectively throughout the room, and that it’s not obstructed by pieces of furniture or hidden away in a corner.
Do air purifiers protect you from getting sick?
According to recent studies, air filtration simulation experiments quantitatively showed that an air cleaner equipped with a HEPA filter can continuously remove SARS-CoV-2 from the air. While many companies are hesitant to make sweeping claims about COVID prevention, some have their air purifiers independently tested, like Coway’s, which have demonstrated a 99.98% removal of COVID-19 in under two minutes. This effectiveness is especially good news in winter, when people tend to migrate indoors and spread sickness more readily. Then again, viruses typically spread through person-to-person contact, so if you’re sitting two inches away from someone who’s infected, that air purifier won’t help much.
If you want to specifically keep one room clean from, say, allergy-inducing pet dander, make sure to keep it relatively sealed tight with an air purifier running before you enter. Nimmagadda recommends focusing on your specific allergies. For instance, if you’re allergic to tree pollen, keep windows closed in the springtime.
But unless there’s serious air pollution outside, you don’t want to keep your windows permanently closed as fresh air is important for the quality of your air. “One of the theories of why asthma and other [respiratory] illnesses are on the rise is because these new homes that we build are so airtight that they don’t really have fresh air exchanges for getting rid of dust mites or indoor smoke,” says Nimmagadda.
How we chose these air purifiers
This guide only includes products that feature a true HEPA filter, which traps 99.97% of particles 0.3 microns in size or larger from the air, including numerous airborne allergens, viruses, and other pollutants. Besides filtration and design, we noted each purifier’s ease of use, smart features, portability, and its recommended square footage for purification. Above all, we selected options you’d actually want to display in your home, since many people keep these things running every day of the year. All of our favorite air purifiers also came with useful features such as air quality indicator lights, voice control, or accompanying apps that make it easy to monitor indoor air quality.
Compared to past versions of this guide, we’ve delisted some Levoit models that didn’t use a true HEPA filter and also older versions of Blueair and Coway air purifiers (the Blue Pure 311 Auto and the Coway Airmega AP-1512HH) for sleeker, smarter options in the same price range.
