Alen's BreatheSmart 25i lists 40 dB at its highest speed, and that is the speed its allergy numbers describe: ENERGY STAR lists its clean air delivery rate, or CADR, at 105 CFM for pollen and 106 for dust, and the Asthma and Allergy Foundation of America's program lists it as certified asthma & allergy friendly. Among purifiers with a published pollen and dust CADR, 40 is the lowest full-speed figure we found, whichever of the two units Alen prints you read it in. The catch is size: those ratings suit a room of about 150 sq ft. For a 12 by 14 foot bedroom, its sibling the 35i lists 42 dB at full speed, with 195 for pollen and 164 for dust.
We judged every purifier on this page at full speed because AHAM, which runs the CADR test, rates pollen, dust and smoke at a purifier's highest setting and at no other. Then we went through what each maker publishes about its slower speeds, checked every model against the certifier's own US listing, and quoted each HEPA claim beside the test it names. This page reports what the certification and the CADRs measure, and it leaves allergy symptoms and health outcomes out.
Our picks are listed above, with full specifications for each.
Three CADRs from one test, at one speed
AHAM's test method, ANSI/AHAM AC-1, gives each purifier three clean air delivery rates, for tobacco smoke, dust and pollen, which AHAM's FAQ says represent fine, medium and large particles. The size ranges it tests are 0.09 to 1.0 microns for smoke, 0.5 to 3.0 for dust and 0.5 to 11.0 for pollen. AHAM's own summary of the result is short: "The higher the CADR number for each pollutant, the faster the unit filters the air."
Two details of that test decide how a purifier for pollen and dust should be read. The first is the speed. The FAQ asks whether every speed of an air cleaner is tested, answers "No", and says the test "is performed in the highest speed setting." A pollen CADR of 195 therefore describes the 35i on Turbo at 42 dB, not on speed 1 at 23 dB, and the same goes for every rating on this page.
The second is the room. AHAM's suggested room size is the smoke CADR multiplied by 1.55, because smoke is the smallest of the three test particles; pollen and dust do not enter the sum. On all seven picks the pollen CADR is above the smoke CADR, so a room size read from smoke is the cautious one for pollen. Dust runs closer, and on one pick it is lower: ENERGY STAR lists the Alen 75i at 351 for dust and 370 for smoke, the figure its 574 sq ft comes from.
For a room of your own, AHAM's rule of thumb is a CADR of at least two-thirds of the floor area. Its worked example is a 10 by 12 foot room of 120 sq ft, where "It would be best to have an air cleaner with a smoke CADR of at least 80." A 12 by 14 foot bedroom of 168 sq ft needs 112 on the same arithmetic, and AHAM adds that "If your ceilings are higher than 8 feet, an air cleaner rated for a larger room will be necessary."
What the asthma & allergy friendly mark checks
The certification program is run by the Asthma and Allergy Foundation of America together with Allergy Standards Limited, which developed the standards it tests against. For an air cleaner, each listing on the certifier's site says the product was tested to ensure that it:
- "Removes allergens from the air"
- "Captures allergens so that they are not redistributed on surfaces around the room"
- does both "without exposure to ozone above designated limits."
None of the three criteria concerns sound, and no listing publishes a result. The mark tells you a purifier passed the program's allergen and ozone tests; it tells you nothing about how loud that purifier is at the speed those tests used.
On October 13, 2026, the certifier's US list of portable air cleaners had sixteen entries:
- Alen: the BreatheSmart 25i, certified October 23, 2025, and the 35i, 45i and 75i, each certified January 31, 2025.
- Rabbit Air: the A3, certified December 24, 2020, and the MinusA2 as the SPA-780A, certified March 25, 2011, and the SPA-780N, certified April 17, 2018, each under its "Asthma & Allergy Friendly®" edition name.
- Blueair: the Classic Pro CP7i, certified September 19, 2024.
- LG: seven PuriCare 360 and AeroTower entries, some under internal names such as "LG 360 Hit_NANO HEPA Filter Air Purifier", with no US model numbers.
- CleanForce: the Rainbow Air Purifier, for which we found no maker page of its own to quote.
Not one Coway, Levoit, Winix, Medify or IQAir model was on the list, and neither was any of Blueair's Blue Pure range.
Rabbit Air sells its certified models as special editions that come "preselected with the Odor Remover customized filter", at the standard prices: $749.95 for the A3, and $599.95 for the MinusA2 SPA-780A or $619.95 for the WiFi SPA-780N. Its standard A3 page, which offers four customized filters, says nothing about the certification, so the editions are what we list. Rabbit Air also sells a Pet Allergy customized filter for both models; if the purifier will share a room with a dog or cat, our pet purifier guide is the one to read.
The listings print product features beside the status, and those do not always match the makers' pages. The certifier's entry for the Alen 45i gives 23 and 49 dB, with airflow of 70, 135, 175 and 215 CFM; Alen's own page says 24 and 50 dB, and 80, 120, 190 and 255 CFM. We rank on the makers' pages.
Full speed, ranked like with like
Alen prints dB in the spec tables of the 25i, 35i and 45i and dBa in the 75i's, while its comparison table prints dBA for all four. The A in that table is an A-weighting, a different scale from plain dB, so we put each Alen in the group its own spec table names. Blueair prints plain dB, and Rabbit Air and Medify print dBA.
Plain dB, at the highest setting, with the pollen and dust CADR:
- Alen BreatheSmart 25i: 40 dB; 105 and 106 (ENERGY STAR); certified.
- Alen BreatheSmart 35i: 42 dB; 195 and 164 (ENERGY STAR); certified.
- Blueair Blue Pure Mini Max Auto: 44 dB; 76 and 64 (AHAM's directory); not certified.
- Blueair Blue Pure 411i+ Max: 46 dB; 189 and 174 (Blueair); not certified.
- Blueair Blue Pure 311i Max: 50 dB; 365 and 314 (Blueair); not certified.
dBA, at the highest speed, with the pollen and dust CADR:
- Medify MA-14: 48.3 dBA; 77 and 60; not certified.
- Rabbit Air BioGS 2.0: 48.6 dBA; 162 and 149; not certified.
- Medify MA-25: 49.3 dBA; 123 and 123; not certified.
- Rabbit Air A3: 51.0 dBA; 315 and 262; certified edition.
- Alen BreatheSmart 75i: 51 dBa; 431 and 351 (ENERGY STAR); certified.
- Rabbit Air MinusA2: 51.3 dBA; 200 and 193; certified edition.
- Medify MA-50 V3.0: 60.6 dBA; 397 and 379; not certified.
The Alen 45i belongs in neither list. It prints 50 dB on its highest speed, but Alen gives it one CADR of 255, which is also its speed 4 airflow, and ENERGY STAR's finder does not list it, so it has no pollen or dust figure to stand beside the 50.
Two patterns run through the lists. The quietest full-speed figures come with the smallest ratings: the 25i's 40 dB covers 150 sq ft, the Mini Max Auto's 44 dB about 105, and the MA-14's 48.3 dBA under 90. And the three certified machines in the dBA list sit within a third of a decibel of 51, while their ratings are far apart: at that figure the 75i delivers 431 for pollen, the A3 315 and the MinusA2 200. Rabbit Air's 51.0 and Alen's 51 dBa come with no measuring distance either, so setting one maker's rating against another's stops at calling them a tie.
A slower speed for the same room
AHAM's FAQ is plain that a slower speed gives up cleaning: "If you run the air cleaner on a lower fan speed, it is understood that both efficacy and the room coverage will also decrease." It does not say by how much, and only one maker on this page prints a CADR below full speed.
Medify lists "CADR by Speed" for the MA-50 V3.0: 19.0 CFM on speed 1, 90.6 on speed 2, 159.5 on speed 3 and 352 on speed 4, beside 21.2, 32.3, 42.7 and 60.6 dBA. The footnote to that table reads "Smoke CADR when operating at highest fan speed", and Medify names no particle for the three lower speeds. Held against AHAM's rule, speed 2 clears the 80 that a 10 by 12 foot room asks for, at 32.3 dBA, and speed 3 clears the 112 a 12 by 14 bedroom asks for, at 42.7 dBA. Medify's smaller MA-25 prints no CADR below its full speed, which is 49.3 dBA for a smoke CADR of 110.
One caution keeps us from leaning on those margins. ENERGY STAR's listing for the MA-50-V3.0 gives smoke 264, dust 281 and pollen 356, against the 352, 379 and 397 on Medify's page and in AHAM's directory, and speed 2 clears 80 by only about 11 CFM.
Alen and Rabbit Air print the airflow at every speed instead, and AHAM warns against reading one as the other: CADR "is the contribution of clean air to the room, while airflow is just a measure of how much air is moved." Alen's own pages show the gap. The 35i's page gives a single CADR of 190, the same number as its Turbo airflow, while ENERGY STAR's listing for the same machine gives 150 for smoke, 164 for dust and 195 for pollen.
So the airflow tables tell you what share of the full-speed air a slower setting keeps, and nothing about its CADR:
- Rabbit Air A3: speed 4 moves 200 of its 286 CFM at 40.4 dBA, and speed 3 moves 144, about half, at 33.5 dBA.
- Rabbit Air MinusA2: speed 4 moves 159 of its 218 CFM at 44.5 dBA, and speed 3 moves 112 at 37.4 dBA.
- Alen 35i: speed 3 moves 135 of its 190 CFM, with no noise figure between 23 and 42 dB.
- Alen 75i: speed 3 moves 255 of its 375 CFM, with nothing printed between 25 and 51 dBa.
That is the argument for buying more rating than the room needs. On AHAM's formula the A3's smoke CADR covers about 398 sq ft, so in a 168 sq ft bedroom it has room to run on speed 3 or 4, where Rabbit Air lists 33.5 and 40.4 dBA; what CADR it delivers there, Rabbit Air does not say.
HEPA, in each maker's words
The EPA describes a HEPA filter as "a type of pleated mechanical air filter", as defined by the U.S. Department of Energy, that "can theoretically remove at least 99.97%" of airborne particles of 0.3 microns, the size it calls the most penetrating. Each maker on this page words its own claim differently, and only Medify and LG tie theirs to 0.3 microns:
- Alen: a "Medical-grade HEPA filter" that "Captures 99.9% of airborne particles as small as 0.1 micron". The 35i and 75i boxes list a "True HEPA air filter", and the 75i's FAQ calls its filters "medical-grade H13 True HEPA". Alen names no test.
- Rabbit Air: "BioGS® HEPA", with "over 99.99% removal of ultrafine 0.01-micron particles". The footnote describes a test of whole purifiers "in a test chamber under modified SPS-KACA 002-132:2018 (Korea Air Cleaning Association standard)" at the highest fan speed, and adds that "Results include natural particle decay." That is a room test of the machine rather than a test of the filter alone.
- Blueair: HEPASilent, which "combines electrostatic and mechanical filtration". The 99.97% on its pages is footnoted "Tested on PM 2.5 up to 90 mins".
- Medify: "HEPA filter material for removal of particles down to 0.3 microns", footnoted "Tested by Intertek Lab for HEPA filter material."
- LG: "NanoFiber True HEPA", footnoted to third-party testing of filter efficiency at 0.3μm "at a flow rate of 8.5 cubic meters/minute".
The CADR is the figure AHAM defines for the whole machine, which is why the rankings above use it and not the filter wording.
Pollen Mode, sensors and the night
A purifier left on an automatic setting can climb all the way to its full-speed figure, so in a bedroom that figure is also the ceiling of the night.
- Rabbit Air MinusA2: the only pick with a Pollen Mode. The SPA-780A manual says that in Pollen Mode, once Sleep Lighting has switched the lights off in a dark room, "the fan speed of the air purifier will continue to change based on the amount of impurities in the air." In Auto Mode the same darkness changes the fan to silent, which Rabbit Air lists at 25.6 dBA, so Pollen Mode is the one that can still reach 51.3 dBA at night.
- Rabbit Air A3: Auto Mode only. When the sensors pick up particles or odors, Rabbit Air says "The machine switches over to high speed until the air has been cleaned", which is 51.0 dBA. Tapping the Auto Mode button cycles the sensor sensitivity, and once the light sensor is switched on, it turns every light off after three minutes of darkness.
- Alen: every model sets its own speed from its sensors, so the 35i's automatic setting can reach 42 dB and the 75i's 51 dBa.
- Medify MA-50 V3.0: no auto mode, and a Sleep Mode of 21.7 dBA that sets the fan to speed 1, where Medify's CADR is 19.0 CFM.
- Blueair 411i+ Max: Auto and Night settings beside speeds 1 to 3.
Filters for a purifier that never stops
Alen states its filter life "@ Recommended 24/7 operation": 9 to 12 months for the Essential filter in the 25i, at $44, and in the 35i, at $54, and 12 to 15 months in the 75i, at $99. The MinusA2's manual asks for its pre-filter to be cleaned every 3 months. Medify rates the MA-50 V3.0's filter at 2,500 hours, which it puts at 3 to 4 months, and Blueair says the 411i+ Max's filter lasts up to a year, tracked by its RealTrack algorithm.
How we chose
We began with the certifier's US list of portable air cleaners and our air purifier catalog, and kept models whose makers label the figure at full speed and whose pollen and dust CADRs come from the maker, AHAM's directory or ENERGY STAR. On October 13, 2026, we read each maker's US product page, Rabbit Air's comparison table and the MinusA2 manuals, Medify's table of CADR by speed, AHAM's FAQ on the AC-1 test and its directory, ENERGY STAR's product finder, and the certifier's listing for every model it names. We ranked full-speed figures only within one unit, placed each Alen in the group its spec table names, and moved certified models that print no full-speed figure, or that were sold out, to the models we also considered. The picks run from the smallest room rating to the largest, with Medify last as the one model documented below full speed.
We did not measure any of these air purifiers: the decibel figures are Alen's, Blueair's, Rabbit Air's and Medify's own, the pollen and dust CADRs come from those makers, AHAM's directory or ENERGY STAR, and each certification is as the Asthma and Allergy Foundation of America's program lists it.
