We do not test air purifiers. We compile the certified Clean Air Delivery Rate, apply the published room-sizing rule, and compute what each machine costs to run — so you can check every number yourself.
The top pick from each roundup, with its certified figures and a live price. Every ranking behind these is derived from AHAM’s directory or EPA’s ENERGY STAR database.
265 CFM certified · 410 sq ft
The best-evidenced pick for a pet household: the highest certified smoke CADR of any mid-price unit here, no ion generator, and a measured zero on ozone.
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265 CFM certified · 410 sq ft
The best-evidenced pick for a pet household: the highest certified smoke CADR of any mid-price unit here, no ion generator, and a measured zero on ozone.
#ad We earn a commission if you buy through this link, at no extra cost to you. How this site is funded. Prices last checked September 23, 2026.
239 CFM certified · 370 sq ft
The unit almost every roundup in this category picks. Certified performance is real, but it ships PlasmaWave and it costs 31% more a year to run than Winix's own AT41 for less air movement.
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376 CFM certified · 583 sq ft
The Coway that is actually in a certification register: 376 certified smoke CADR, 583 square feet, zero measured ozone. If you want a Coway, this is the one with third-party numbers.
#ad We earn a commission if you buy through this link, at no extra cost to you. How this site is funded. Prices last checked September 23, 2026.
239 CFM certified · 370 sq ft
The unit almost every roundup in this category picks. Certified performance is real, but it ships PlasmaWave and it costs 31% more a year to run than Winix's own AT41 for less air movement.
#ad We earn a commission if you buy through this link, at no extra cost to you. How this site is funded. Prices last checked September 23, 2026.
435 CFM certified · 674 sq ft
The most air per watt of anything here and by some distance the largest certified coverage — 674 square feet. It does carry an ion generator, which is the reason it is not our asthma pick.
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Certified CADR picks for cat and dog allergen, with the ionizer status of every unit stated up front.
Winix AT41
265 CFM certified · 410 sq ft
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Hair, dust and odor are three jobs. Which machines do each one, and why cheap units never touch the smell.
Blueair DustMagnet 5440i
216 CFM certified · 335 sq ft
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The flagship allergy roundup, the ozone and ionizer safety pages, and what particle size actually means.
Honeywell InSight HPA4300
229 CFM certified · 354 sq ft
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The calculator, the AHAM two-thirds rule, and certified picks for bedrooms, large rooms, small rooms and apartments.
Honeywell InSight HPA4300
229 CFM certified · 354 sq ft
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The cornerstone explainer, the certified CADR comparison chart, and the running-cost arithmetic with its working shown.
Winix C710
248 CFM certified · 384 sq ft
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Everyone in this category says they tested a dozen units. We have not tested any, and we say so. There is no lab here, no owned machines, and no measurements of our own — inventing them would be the easiest thing in the world and the easiest thing to catch.
What we do instead: compile the Clean Air Delivery Rate that AHAM or EPA’s ENERGY STAR program certified, apply AHAM’s published two-thirds sizing rule out loud, convert certified annual energy use into dollars at a rate we name, read each unit’s ionizer status and measured ozone off the register rather than the box, and cite primary sources for every claim about health.
Every one of those inputs is public. That is the point: you can disagree with our conclusions using exactly the same evidence, which is not true of a testing claim nobody can check. The method in full, including where it runs out.
The four pages that carry the argument. If you only read one, make it the CADR explainer.
The cornerstone explainer: what CADR measures, why it resists gaming, and certified versus claimed.
Enter your room dimensions and get the minimum certified CADR, with the arithmetic shown.
The flagship roundup: certified CADR, measured ozone, computed running cost, and the coverage claims checked against the registers.
What EPA advises about ionizers and ozone, with published measurements for every certified unit.
All 80 pages are listed on the sitemap, and new work is published to the Atom feed.
Dander Down earns a commission when you buy through our links, at no extra cost to you. We are a participant in the Amazon Services LLC Associates Program. Commission never decides a ranking: picks are selected against the criteria published on How We Pick before affiliate availability is looked at, and we accept no free products, sponsored placements or paid inclusions.