Each review works from the manufacturer’s own documentation and the AHAM Verifide directory. Where a figure is not published, we say so instead of estimating it — and coverage is always shown with the air-change rate behind it, because otherwise the square footage means nothing.
4 reviewed
Blueair
AHAM Verifide at 353 cfm smoke CADR for a 550 sq ft room, and Blueair publishes exactly those numbers rather than a flattering pair — which almost nothing else in this catalogue does. It draws 4 W on its lowest speed.
Blueair
AHAM Verifide at 283 cfm smoke for a 439 sq ft room, and the rare case where the electrostatic question has an actual number attached: ENERGY STAR measured its ozone emission at 2 ppb.
Blueair
A compact tower with an AHAM Verifide smoke CADR of 123 cfm and a 190 sq ft AHAM room size. CARB classifies it Electronic, which is a consequence of how Blueair's HEPASilent works rather than a fault.
Blueair
A 4.2 lb, three-speed, single-button room air purifier using one combined particle-and-carbon filter behind a washable fabric pre-filter, AHAM Verifide at 122 cfm smoke CADR and measured by AHAM at 14.2 W at that rated output (Blueair rates energy consumption at 16 W).
2 reviewed
Coway
A large twin-intake tower Coway rates at 328 cfm smoke CADR. Its headline 3,120 ft² is quoted at ONE air change per hour; at AHAM's 4.8 the comparable figure is about 508 ft².
Coway
The Coway Airmega Mighty AP-1512HH is a 12.3 lb portable room air purifier that Coway rates at 361 sq ft (4.8 air changes per hour) using a washable pre-filter, an activated-carbon deodorization filter, a filter Coway labels True HEPA, and a bipolar ionizer stage that has its own on/off button.
1 reviewed
GermGuardian
A 22-inch tower with a UV-C lamp, rated by GermGuardian at 99 cfm smoke CADR. Its honest coverage figure is 153 sq ft — the 743 sq ft in the listings is the same machine at roughly one air change per hour.
2 reviewed
Honeywell
AHAM Verifide at 200 cfm smoke for 310 sq ft, and Honeywell is one of the very few brands that prints the air-change basis next to the room size instead of leaving you to work it out.
Honeywell
A two-stage mechanical purifier that holds three Type R "True HEPA" filters behind one Type A pre-filter, AHAM Verifide at 300 cfm smoke CADR with a 465 sq ft AHAM suggested room size.
6 reviewed
Levoit
An AHAM Verifide smoke CADR of 90 cfm and a 140 sq ft room size — and unusually, Levoit's own specification table prints exactly the same 140 sq ft the certifying body does.
Levoit
A three-stage air purifier with a laser dust sensor, Wi-Fi and Auto Mode. Levoit rates it at 141 CFM and gives an ideal room size of 219 ft² at 4.8 ACH, and AHAM Verifide lists the Core 300S at exactly those figures — but the unit shipping today may be the 300S-P, which AHAM records with an ion generator.
Levoit
A three-stage smart tower that Levoit rates at 231 CFM and sizes at 358 ft² at 4.8 air changes per hour. CARB certifies it as Mechanical, and AHAM Verifide independently measures it at that same 231 cfm smoke and that same 358 sq ft.
Levoit
AHAM Verifide at 34 cfm smoke and sized at 53 sq ft — against a 254 sq ft figure on the box. The gap between those two numbers is the widest in this catalogue, and both are Levoit's.
Levoit
AHAM Verifide at 143 cfm smoke and 222 sq ft — figures Levoit reprints exactly — with a washable pre-filter and a choice of four carbon cartridges.
Levoit
AHAM Verifide at 250 cfm smoke across 388 sq ft, with a washable pre-filter and a sensor-driven auto mode — the biggest CARB-Mechanical machine in this catalogue.
2 reviewed
Medify Air
AHAM Verifide at 110 cfm smoke for 170 sq ft, with a published noise figure for every single fan speed — and a room size Medify gets wrong by two square feet in its own favour.
Medify Air
A three-stage tower with an AHAM Verifide smoke CADR of 239 cfm and a 370 sq ft AHAM room size. Medify states its filter life in hours rather than months, which almost no other brand does.
3 reviewed
Winix
A 4-stage tower air purifier - permanent pre-filter, washable AOC carbon filter, a filter stage Winix calls True HEPA, and a switchable PlasmaWave ionizing stage - AHAM Verifide for 370 sq ft at 4.8 air changes per hour.
Winix
AHAM Verifide at 265 cfm smoke across 410 sq ft, and the clearest answer in this catalogue to the ionizer question: CARB calls it Electronic, and two separate laboratories put its ozone emission at essentially nothing.
Winix
AHAM Verifide at 461 cfm smoke across 714 sq ft — by a wide margin the largest machine in this catalogue — with a pollen CADR that runs off the top of AHAM's own scale.
Work from CADR, not from the box. Multiply the room’s floor area by the ceiling height to get its volume, then check what the smoke CADR gives you: a CADR in cubic feet per minute, times 60, divided by the room volume, is roughly the air changes you get per hour at top speed. AHAM sizes rooms at 4.8 of those. Two things to keep in mind: that figure is at MAXIMUM fan speed, which is usually the setting nobody can sleep through, and a purifier in a room with the door open is working on a much larger volume than you measured.
Somewhere the air can actually reach it: manufacturers generally ask for clearance around the intake and outlet, and pushing a unit into a corner or against furniture starves it. Beyond that, the honest answer is that placement advice online is mostly repeated without measurement. Follow the clearance your own manual states — it is the only placement figure that comes from whoever built the machine.
They are a different technology from filtration, and the first question is whether you can switch the stage off. Some units make the ionizing stage a button; in others it is integral to how the machine filters at all. California classifies devices with an electronic stage separately from purely mechanical ones and tests them against an ozone limit. On every review here we state what the stage is, whether the manufacturer documents a way to turn it off, and where the manufacturer says nothing.
Because they move, and a price quoted on a page goes stale the same week while still looking authoritative. The Amazon button opens the current listing, which is the only place the figure is ever right. What we do publish is the part of the cost that does not move: how many filters a year the unit consumes, and which stages are washable.
