How We Chose

First, we looked at the landscape of air purifiers. Air purifiers use combinations of HEPA filters, activated carbon filters, UV sanitizers, and ionizers to clean the air. Unfortunately, UV sanitizers and ionizers can produce small amounts of ozone.

Though many air purifiers with ionizers and UV sanitizers have passed strict government ozone limits, long-term ozone exposure is potentially dangerous. Ozone production aside, UV sanitizers add marginal value to HEPA filtration, according to the EPA.

Upon learning this information, we decided to focus on filter-only air purifiers. We cross-referenced professional reviews with Amazon reviews and our own experiences with air purifiers. We considered design, weight, and keeping the noise level lower than an air conditioner in addition to the purifiers’ HEPA filter designations. Finally, we made sure the purifiers we chose met the California Air Resources Board’s (CARB) strict standards for air purifiers and were listed as “Mechanical.”

“Long-term ozone exposure is potentially dangerous.”

What to Look for in an Ozone-Free Air Purifier

Without the additions of ionizers or UV sanitizers, air purifiers are only as good as their filters. Other features can inform your decision, but HEPA designation should be your main consideration.

HEPA Filters: HEPA stands for High Efficiency Particulate Air. True HEPA filters catch 99.97 percent of particles 0.3 microns and larger while HEPA Type filters usually catch 85–99 percent of particles 2–2.5 microns and larger.

True HEPA is ideal if you are looking for allergy or smoke relief, but the HEPA Type filters are effective against larger pollutants like dust and pet dander. Though HEPA filters play a role in deodorization, pre-filters and carbon filters usually do most of the legwork in removing odors.

Replacement Filter Cost: You should take into account how much it costs to replace your filter and (if applicable) pre-filter. Depending on how often you need to change each filter, this can greatly impact your purifier’s cost over time.

Control Panel Lighting: If you’re planning on putting an air purifier in your bedroom and you are sensitive to light, you should look for a purifier with minimal, dimmable, or no lights at all.

Noise: Virtually every air purifier is noticeable on its highest setting. The lower settings should be tolerable or almost silent. The loudness threshold will vary from person to person as well as by the acoustics of the room where you place the air purifier.

Clearance: Depending on where the air purifier’s intake and outtake vents are, you’ll need a little space between the machine and other objects or walls. Some purifiers can hug a wall while others need a few inches to work to their highest capacity.

Timer: Want to set it and forget it? Timers come in handy so you’re not burning through energy. Many air purifiers will change the air in their recommended room coverage at least twice within one hour. Unless there’s a lot of air being introduced from other parts of your home/outside through doors and windows, or you are dealing with a persistent smell like a litter box, the purifier doesn’t need to be on all the time.

Pollution Sensors: If you don’t want to fiddle with controls at all, look into pollution sensors. High-end air purifiers will include pollution sensors that can turn the machine on/off and even change the fan speed based on the air quality.

Close, But No Cigar

We looked closely at Blueair’s Blue Pure 211+ and a few Winix air purifiers, but discovered that they both use ionizers. We had to ask Blueair directly since they don’t publicly market the ionizers in their Blue line of products (they even go so far as to say the 211+ is ozone free). We also discovered Winix’s Plasmawave feature is just a proprietary ionizer.

“When you try to put multiple devices in one machine, it’s rare that all of them work well.”

The Coway AP-1512HH, which is highly rated on Amazon, was high on our list since the ionizer is optional and the design is sleek. We discovered that a few users noticed an increased ozone smell even when the ionizer was turned off. As a result, we omitted purifiers with optional purifiers from our guide.

We also considered Dyson’s Pure series of air purifiers because they would look great in your spaceship living room. In addition to purifying the air with a suite of smart features, these machines also work as fan and/or a heater. Unfortunately, all the bells and whistles in the world couldn’t help its real world filtration performance compared to the Airmega 300, according to Wirecutter.

When you try to put multiple devices in one machine, it’s rare that all of them work well, which is why we omitted Dyson’s air purifiers as well as any purifier-humidifier combos from other companies.