How to choose an air purifier for smoke

A HEPA filter does the work on smoke

Most portable air purifiers catch particles with a pleated filter and a fan. The EPA says the ones with high clean air delivery rates often get there with a HEPA (high-efficiency particulate air) filter. A HEPA filter captures at least 99.97% of particles 0.3 microns across, and catches larger and smaller particles even better.

The California Air Resources Board (CARB) recommends HEPA or other high-efficiency filter models because they remove more of the small particles of concern and don't emit ozone.

No purifier removes everything. The EPA notes that most filters are built for either particles or gases. A HEPA filter handles smoke particles. For gases and odors, you need an activated carbon filter as well, and the EPA says carbon works best when there's a lot of it.

Size it by the smoke CADR

CADR (clean air delivery rate) is how much filtered air a purifier puts out, in cubic feet per minute. The label gives 3 numbers: tobacco smoke, dust and pollen. Smoke stands in for the smallest particles, so that's the one to use for wildfire smoke. The rating is usually measured at the highest fan speed.

The Association of Home Appliance Manufacturers (AHAM), which runs the CADR test, gives a 2/3 rule: the smoke CADR should be at least two-thirds of the room's floor area in square feet. For wildfire smoke, AHAM suggests a smoke CADR equal to the room's square footage.

Measure length times width. These numbers assume 8-foot ceilings. With higher ceilings, AHAM and the EPA say to go bigger. For an open floor plan, the EPA says to count the whole space, and to use more than one unit if no single model is big enough.

Don't oversize it, though. AHAM warns that a unit too large for the room means unnecessary energy use and noise, and CARB says the same.

Look for 2 labels

AHAM Verifide. This label shows the CADR and a suggested room size. AHAM says units are picked at random and tested at an independent lab under the ANSI/AHAM AC-1 standard. You can search certified models in AHAM's directory.

CARB certified. California requires every air cleaner sold there to be tested for electrical safety. Electronic models must also stay at or under an ozone limit of 0.050 parts per million. Certified units carry the label "Meets California ozone emissions limit: CARB certified." The list of certified devices is public, so you can check a model from any state.

The EPA does not certify or recommend brands of air cleaners. An ENERGY STAR label is about electricity use only. It says nothing about how well a unit cleans the air.

Skip anything that makes ozone

Ozone is a lung irritant. Some machines sold as air purifiers make it on purpose. The EPA says no federal agency has approved these ozone generators for occupied spaces. At levels that stay within health standards, ozone does little to clean indoor air, and it doesn't remove particles at all. It can also react with other chemicals indoors and form irritating byproducts.

Watch for marketing names. The EPA and CARB list "energized oxygen," "pure air," "activated oxygen" and "super-oxygenated air" as terms sellers use for ozone.

Other technologies need caution. The EPA says electrostatic precipitators, ionizers, UV lights without proper coatings, and plasma cleaners may give off ozone in some cases. In experiments it cites, ionizers removed less dust, smoke and pollen than high-efficiency filters. The EPA also says research hasn't shown that plasma, photocatalytic oxidation or UV light remove gases well in home portable units. CARB advises using newer technologies only after careful thought, since some may produce ozone or other pollutants.

Our ozone guide has more on why ozone matters.

Count the cost of running it

Filters. All filters need regular replacement, and the EPA says a dirty, overloaded filter won't work well. During smoke, plan to change it more often than the manual says. Check what replacement filters cost before you buy the unit. AHAM now runs a Verifide program for replacement filters, tested to match the original maker's filter.

Electricity. ENERGY STAR says a standard room air cleaner running nonstop uses about 394 kWh a year. Certified models are more than 50% more efficient, which ENERGY STAR says saves about 211 kWh and $18 to $40 a year, depending on size.

Price. CARB's 2020 fact sheet put small portable units at $50 to $200 and larger or more efficient ones at over $300.

Noise decides whether you run it

The EPA says higher fan speeds and longer run times filter more air. During smoke, it says to run the unit on high in the room where people spend the most time. A unit you turn off because it's loud isn't helping.

Some packaging lists a noise rating. Noise depends on the fan speed. For reference, the EPA says about 50 decibels is roughly a modern refrigerator.

Place it where air can flow freely. AHAM suggests closer to the center of the room. CARB says keep it away from doors, windows and foot traffic, and out of corners.

Our picks

We name a purifier only when its smoke CADR is in AHAM's directory and California certifies it as a mechanical cleaner. As of November 2026, 3 models met both tests and gave the most verified smoke cleaning for the money.

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