Smoke changes what quiet means for an air purifier. In a bedroom you buy on the low figure and run the slowest speed all night. During a wildfire, the EPA's advice is the opposite: run the purifier as often as possible on its highest fan speed. Smoke from a pan or a cigarette is shorter, but the auto mode on most purifiers answers it the same way, by going to high.
So this guide ranks purifiers on two figures. The first is the maker's noise figure at the speed that delivers its stated smoke CADR, which is the top speed. The second is the figure at the lowest speed, for the long tail after the smoke thins. It is the smoke follow up to our main guide to the quietest air purifiers, which explains why the airflow rating and the quiet figure on the box describe opposite ends of the machine. We cover noise, airflow and filters only, and we have left the makers' health claims out.
Our picks are listed above, with full specifications for each.
Why smoke is about the top speed
AHAM, which runs the Verifide program, says CADR comes "with separate scores for tobacco smoke, pollen and dust", and that the higher the number, the faster the unit filters the air. The EPA explains why the smoke score is the one to read: the three pollutants "are used as examples to represent small-, medium-, and large-sized particles", and to remove small particles you should "choose a portable air cleaner that has a high CADR for tobacco smoke, which represents the smallest particles."
The catch for quiet is where that rating is measured. The EPA says CADR "is typically measured at the air cleaner's highest speed," and its guide adds that an air cleaner "will filter less air if it is set at a lower speed." Medify is the only maker here that says so on its own page, in a footnote on every model: "Smoke CADR when operating at highest fan speed."
So for each purifier, the noise that goes with its smoke CADR is the top figure. That is a problem, because many makers print a range without saying which setting the top end describes. Coway's Airmega Halo is an example: it ties 17.8 dB(A) to Sleep Mode but gives no setting for 52.13. Winix prints only its slowest speed. We can quote those, but we cannot rank them at full speed.
Sizing for wildfire smoke, as AHAM states it
AHAM's everyday rule of thumb is that "the CADR of your air cleaner should be equal to at least two-thirds of the room's area." Its example is a 10 by 12 foot room of 120 sq ft, which should have "a smoke CADR of at least 80."
Wildfire smoke gets a stricter line. On the same page AHAM says: "For wild fire smoke, AHAM recommends a Smoke CADR equal to the size of the room in square feet." It adds that "If your ceilings are higher than 8 feet, an air cleaner rated for a larger room will be necessary."
That is why our spec tables carry a "Wildfire room (AHAM)" line: it is simply the smoke CADR read as square feet. Here is how our picks fall:
- About 110 to 170 sq ft, a typical bedroom: Medify MA-25 (110), Rabbit Air BioGS 2.0 (136), Blueair 411i+ Max (167).
- About 250 sq ft, a large bedroom or small living room: Coway Airmega Halo (253.3), Rabbit Air A3 (257).
- About 350 to 450 sq ft, a living room: Medify MA-50 V3.0 (352), Blueair 211i Max (435).
The bedroom units in the first group are fine for everyday use in a bigger room. On AHAM's two-thirds rule, the BioGS 2.0 covers about 204 sq ft. For wildfire smoke, by AHAM's own guidance, they belong in a smaller room. Our large room air purifier guide works through bigger spaces in more depth.
Ranking at full speed, like with like
Makers print noise in two ways. Some write dBA or dB(A), which says the figure is A-weighted to match human hearing. Others write plain dB. We do not rank one against the other, and no maker here states a measuring distance, so treat a gap of a decibel or two as a tie. Our dBA explainer covers the difference.
A-weighted figures, at the highest speed, with the smoke CADR:
- Rabbit Air BioGS 2.0: 48.6 dBA, smoke CADR 136
- Medify MA-25: 49.3 dBA, smoke CADR 110
- Rabbit Air A3: 51.0 dBA, smoke CADR 257
- Rabbit Air MinusA2: 51.3 dBA, smoke CADR 180
- Medify MA-40: 53.3 dBA, smoke CADR 239
- GermGuardian AC4825: 55 dBa, smoke CADR 99
- Medify MA-50 V3.0: 60.6 dBA, smoke CADR 352
Plain dB figures, on the high setting, with the smoke CADR:
- Blueair Blue Pure 411i+ Max: 46 dB, smoke CADR 167
- Blueair Blue Pure 311i Max: 50 dB, smoke CADR 283
- Blueair Blue Pure 211i Max: 53 dB, smoke CADR 435
- IKEA STARKVIND: 53 dB with the particle filter only, AHAM tobacco smoke CADR 123
Read both lists against the CADR, not just the decibels. The quietest full-speed figures belong to small units that clear small rooms. The Rabbit Air A3 is the interesting one: 51.0 dBA is only 2.4 dBA above the BioGS 2.0 for nearly twice the smoke CADR. The Medify MA-50 V3.0 sits at the other end. It is the loudest at full speed, but it has the most published data below full speed, which matters more than it seems.
We left Alen out of the ranking. Alen prints labelled figures, such as "Lowest Speed - 23 dB | Highest Speed - 42 dB" for the 35i, but its own page gives a single CADR of 190 CFM without saying whether that is smoke, dust or pollen. ENERGY STAR lists the 35i at a smoke CADR of 150, which is not the maker's figure. Our Alen air purifier decibels page has the full Alen line.
The speed below full, where Medify shows its working
A purifier rated well above your room can run one speed down and still keep up. The trouble is that almost no maker tells you what that lower speed delivers. Medify does, on two models, and it changes the choice.
The MA-50 V3.0 lists "Speed 3: 159.5 CFM (271 m³/h)" of CADR, and 42.7 dBA at that speed. On AHAM's wildfire guidance applied to that lower figure, which is our own extension of the rule, Speed 3 would carry a room of about 160 sq ft. That is more than the MA-25 delivers at full speed (110 CFM at 49.3 dBA). So in a small bedroom during a smoke event, Medify's own figures say the bigger unit, one speed down, is both quieter and moves more clean air.
The MA-40 shows the limit of that idea. Its CADR by speed starts at 144.3 CFM on Speed 1, but at 40.5 dBA, and Medify lists Sleep Mode at the same 40.5 dBA. Nothing on it goes below 40.5 dBA.
Rabbit Air publishes airflow at every speed, from 64 to 286 CFM on the A3, with the noise beside it: 40.4 dBA at 200 CFM on Speed 4, for example. Airflow is not CADR, so we do not set those numbers against Medify's. Every other maker here prints the two ends and nothing between.
Ranking at the lowest speed
When the smoke has cleared, or for a nightly run after a cooking session, the low figure matters again. Two caveats apply: many low figures belong to a sleep mode slower than the first speed, and the airflow there can be tiny. The MA-50 V3.0's Speed 1 moves 19.0 CFM.
A-weighted, lowest setting: Coway Airmega Halo 17.8 dB(A) in Sleep Mode; Medify MA-25 19.8 dBA on Speed 1; Rabbit Air A3 20.3 dBA; Medify MA-50 V3.0 21.2 dBA on Speed 1; Rabbit Air BioGS 2.0 22.8 dBA; Rabbit Air MinusA2 25.6 dBA.
Plain dB, lowest setting: Blueair 411i+ Max 19 dB; Blueair 311i Max and 211i Max 23 dB each; Winix 5510 23.5dB on its slowest speed; IKEA STARKVIND 24 dB.
If the purifier ends up running all night in a bedroom, our bedroom air purifier guide and the quiet bedroom checklist cover lights, sleep modes and placement.
Gases and odor: carbon, and how much
Smoke is not only particles. The EPA describes it as "a complex mixture of gases and fine particles." A HEPA filter is for the particles. For the rest, the EPA is plain: "The CADR rating system is for particles only." To filter gases, it says, choose an air cleaner with an activated carbon filter, and "Activated carbon filters can be effective, provided that there is a large amount of material used in the filter." It also notes that there are no widely used performance rating systems for gas filters.
So the useful question is how much carbon a filter holds, and very few makers answer it:
- IQAir is the one maker we found that weighs its gas media. The HealthPro Plus XE's V5-Cell holds "MultiGas granulated activated carbon & impregnated activated alumina", "Weight: 5 lbs. (2.5 kg)". That is a blend, not all carbon. IQAir publishes no smoke CADR for it, and our IQAir decibels page covers its figures.
- Blueair gives a ratio, not a weight: its SmokeBlock filter has "2x more activated carbon than our original filter."
- Rabbit Air describes a Dual Hive filter of "high-grade granular activated carbon in two staggered layers", with no weight.
- Medify says each pick has a "Substantial carbon filter with carbon pellets to remove odors and smoke", with no weight.
- Coway lists a "Deodorization Carbon Filter" in the Halo's 3-in-1 filter, with no weight.
No maker here says whether a heavier carbon filter changes the noise. IKEA is the only one that shows a filter changing the figures at all: with its gas filter fitted, the STARKVIND's top airflow drops from 158 to 141 CFM and its top noise from 53 to 51 dB. Its AHAM tobacco smoke CADR of 123 was tested with the particle filter only, so it does not describe the unit with the gas filter fitted.
Cooking and tobacco smoke: short bursts, auto modes
Cooking and cigarette smoke come in bursts, and an auto mode reacts to each one. Rabbit Air describes what happens on the A3: when the sensor detects particles or odors, "The machine switches over to high speed until the air has been cleaned." That is 51.0 dBA, by Rabbit Air's figure, every time someone sears a steak. The A3 lets you turn the sensor sensitivity down to Low. The Medify picks have no auto mode, so they stay at the speed you choose.
For cooking, the purifier is the second line. A range hood takes smoke out at the stove, before it spreads, and our guide to quiet range hoods for an open kitchen ranks them in sones. If the purifier shares an open kitchen and living space, the quiet open plan kitchen checklist covers the other machines in that room.
What quiet costs when there is smoke
- Size. Quiet at full speed comes from small units with small smoke CADRs. Enough CADR for a living room in wildfire smoke means 53 dB on the Blueair 211i Max or 60.6 dBA on the Medify MA-50 V3.0.
- Filters. Smoke loads filters fast. Medify's MA-50 V3.0 filter lasts 2,500 hours, 3 to 4 months, at $69.99. Blueair's SmokeBlock filter for the 211i Max is $84.99, against $69.99 for the standard one.
- Price. The A3, with the best balance of smoke CADR and full-speed noise here, is $749.95. The MA-25 is $148.99.
For every Medify and Rabbit Air model, speed by speed, see our Medify air purifier decibels page and Rabbit Air purifier decibels page. Blueair's full range is on our every Blueair page.
How we chose
We started from purifiers whose makers publish both a smoke CADR and a noise figure, and reopened each maker's product page, comparison table or spec sheet to confirm the figures quoted here. We ranked at the speed that delivers the smoke CADR only where the maker names that speed or labels its top figure, and at the lowest speed only where the maker names that setting. We kept dBA and dB(A) figures apart from plain dB figures, and left out makers whose CADR is not labelled for smoke. For general guidance on smoke, sizing and carbon we used only the EPA and AHAM.
We did not measure any of these purifiers ourselves. Every noise figure, CADR and filter description here comes from the maker's own page or document, no maker states the distance behind its noise figures, and where a maker gives no weight for its carbon we say so rather than guess.
