How Air Purifiers Are Tested
Many performance claims in this category cannot be checked. A brand publishes a percentage, a room size, or other performance numbers, and there is no way for a buyer to know where any of it came from. This page explains the standards that do exist, what each one measures, where they stop, and what our products score against them. Every figure here is traceable to a named laboratory or a public directory you can search yourself.
I chair the AHAM Air Cleaners Council, the industry group that oversees the test standards used across this category.
The Four Standards That Matter
| Standard | Who runs it | What it measures | What it does not |
|---|---|---|---|
|
AHAM AC-1 CADR |
Association of Home Appliance Manufacturers, tested by independent labs | Clean Air Delivery Rate for smoke, dust and pollen, in CFM. Suggested room size at 4.8 air changes per hour. | Gases, odors, noise, ozone, or performance over time |
| AHAM AC-4-2022 | Independent labs. Ours was run by Intertek. | Chemical gas reduction in a room air cleaner. A certification, but participation is optional. | There is no public verified directory, so a result cannot be looked up the way CADR can. |
| CARB | California Air Resources Board | Ozone emission below the state limit. Required to sell in California. | Cleaning performance of any kind |
| ENERGY STAR | US EPA, transitioning to the Department of Energy | Energy efficiency as CADR per watt. Voluntary. Criteria raised sharply in October 2025. | Absolute cleaning performance. An efficient but weak purifier can still qualify. |
Three of the four are certifications. Only one, AHAM AC-1, has a public directory you can search to check a manufacturer's claim. Knowing which is which is most of what separates an informed buyer from a persuaded one.
Two of these are in motion. Administration of ENERGY STAR is transitioning from the EPA to the Department of Energy. And the FTC is reviewing whether to regulate room size coverage claims for air purifiers, which today are unregulated and inconsistent. If that regulation arrives, the expectation is that it will be based on AHAM AC-1 for particles, which would end the practice of quoting whichever air change rate produces the largest number for particle removal.
Particle Performance: AHAM Verifide CADR
CADR is the only certified performance measure in residential air cleaning. A purifier runs at maximum fan speed in a sealed test chamber while a laboratory measures how quickly it removes three particle types. Smoke represents the smallest particles, pollen the largest, dust in between. The result is expressed in cubic feet per minute of clean air delivered.
The number is meaningful because the method is fixed and the testing is independent. AHAM also randomly selects certified products and retests them.
| Model | Smoke CADR | Coverage at 4.8 ACH | Certifications |
|---|---|---|---|
| AirMend™ 150HB | 189 CFM | 293 sq ft | AHAM Verifide, CARB |
| AirMend™ 200HB | 208 CFM | 322 sq ft | AHAM Verifide, CARB |
| AirMend™ 270HB | 237 CFM | 367 sq ft | AHAM Verifide, CARB |
| Mod Jr. | 234 CFM | 363 sq ft | AHAM Verifide, CARB |
| Mod+ | 363 CFM 369 PM2.5 |
563 sq ft | AHAM Verifide, CARB |
Check it yourself. These figures are published in the AHAM Verifide directory at ahamverifide.org. Search any brand, including ours. If a purifier is not in that directory, its CADR has not been independently verified.
Also, some brands market their CADR in cubic meters per hour (m³/h). One CFM equals 1.699 m³/h, so you can see how the CADR can be misrepresented. CFM is the standard in the US.
Why coverage figures are not comparable between brands
A room size claim is close to meaningless unless the air change rate behind it is stated, and it usually is not.
We publish room coverage at 4.8 air changes per hour. That is the AHAM standard, it is the basis of the suggested room size on the AHAM Verifide seal, and it is calculated as CADR multiplied by 1.55.
Another way to think about 4.8 air changes per hour: the purifier filters all the air in the rated space every 12.5 minutes. That is the rate allergists recommend when the goal is controlling an airborne allergen rather than general freshening.
Other manufacturers quote coverage at lower air change rates, which produces a much larger and much more flattering number for the same machine.
When comparing any two purifiers, check that both coverage figures use the same air change rate. If a brand does not say, assume the more flattering one. The formula is in our guide to CADR and room size.
This may not stay unregulated. The FTC is currently reviewing whether to regulate air purifier room size coverage claims, which are today entirely at the manufacturer's discretion. If a rule is issued, the expectation is that it will be based on AHAM AC-1 for particles. We would welcome that. A single mandatory basis would make purifiers comparable in a way they currently are not, and it would remove the incentive to quote whichever air change rate produces the biggest number.
Gas and Odor Performance: Intertek, AHAM AC-4-2022
This is a new standard.
Almost no one has done this test. AHAM AC-4-2022 is a certification covering chemical gas reduction by a room air cleaner, and it is a real test method run by independent laboratories. Two things limit it.
First, participation is optional. A manufacturer can sell a purifier advertising carbon filtration and never submit it for gas-phase testing.
Second, there is no public verified directory. With CADR you can search ahamverifide.org and check any brand's claim in thirty seconds. There is no equivalent for gas performance, so even where a result exists you cannot look it up independently.
The consequence is that when a brand publishes a VOC or odor removal percentage, you generally cannot tell whether it came from AC-4-2022, from a method the brand selected, or from nowhere in particular.
Our TrueCarbon has been tested against AC-4-2022 by Intertek, an independent laboratory. We would rather they were verifiable in a public directory the way a CADR is. Until one exists, naming the standard and the laboratory is the most that can be offered, and it is more than most of this category offers.
| Compound | Represents | Why it is difficult |
|---|---|---|
| Ammonia | Litter box, cleaning products, urine odor | Small polar molecule. Poorly held by untreated carbon. |
| Formaldehyde | New furniture, flooring, cabinetry, paint | The hardest common VOC for plain carbon. Requires treated media. |
| Limonene, toluene, heptane | Cleaning products, solvents, fuels, fragrance | A spread of molecular weights, testing breadth rather than one easy case |
Formaldehyde and ammonia are on that list deliberately. They are the compounds that separate treated carbon from a carbon-coated sheet, and they are the ones a brand would leave out if it wanted a flattering result.
What we publish alongside the lab results
We also publish the specifications that determine gas-phase performance and that you can verify by handling the filter yourself:
- Carbon mass. Over 3 pounds of granular activated carbon per TrueCarbon filter. Most purifiers advertising a carbon filter carry under half a pound in a coated sheet.
- Bed depth. A packed bed 2.2 inches deep, with no gaps for air to bypass the media. Contact time matters as much as quantity.
- Additional media. Potassium permanganate alongside the carbon, which oxidizes compounds rather than adsorbing them. This is why formaldehyde appears in our results.
Weigh a competitor's filter. That single act tells you more than most published claims.
Safety: CARB Certification and Zero Ozone
Every Oransi purifier is certified by the California Air Resources Board, which requires testing to confirm ozone emission stays below the state limit. The certified device list is public at CARB's website.
Our purifiers use mechanical and adsorptive filtration only. No ionizer, no ozone generator, no UV, no plasma, no photocatalytic stage. There is nothing in them that produces ozone as a byproduct because there is nothing in them that generates charge or light.
This matters more than it sounds. Ozone is a lung irritant, and devices that generate it are marketed heavily for exactly the situations where an irritant is least appropriate: mold, smoke, and odor in occupied rooms. The reaction between ozone and common household compounds can also produce formaldehyde and ultra-fine particles.
Any device you are considering should appear on the CARB list. If it does not, it has not been tested against the state limit.
Energy Efficiency: CADR Per Watt
A purifier only works when it is running, and effective use means running it continuously. A machine that is expensive to run gets switched off, and a purifier that is off has a CADR of zero. The efficiency question is really a performance question.
The metric is CADR delivered per watt consumed at maximum speed. It is the basis of ENERGY STAR certification, which is voluntary and whose criteria were raised significantly in October 2025, to the point that the majority of air purifiers on the market no longer qualify. Administration of the program is also transitioning from the Environmental Protection Agency to the Department of Energy.
Our motors are designed around airflow per watt, which is why an AirMend delivers full room coverage from a unit that sits on a table. That design choice is also what keeps noise down at the speeds required to hit the rated CADR, since moving the same air with less power means moving it with less fan.
What These Tests Do Not Measure
CADR is measured at maximum fan speed. If you run the purifier on low because high is too loud, you are getting a fraction of the certified number. Check the decibel level at the speed required to deliver the CADR you need, not the quietest setting advertised.
CADR is measured with a new filter. It describes day one. A thin filter with little media can test well and fall away within months. A large filter with more media holds its performance far longer. Ask how much media is in the filter, and be cautious when a manufacturer will not say.
AC-1 CADR does not measure gases or odors. A high particle CADR tells you nothing about whether a purifier will address smoke smell, cooking odor, or off-gassing. Those are separate mechanisms requiring separate media.
CADR does not measure noise, ozone, energy use, or reliability. Four separate questions, none of them answered by the number on the box.
Gas removal results cannot be independently verified. AHAM AC-4-2022 certification exists, but participation is optional and there is no public directory.
Independent Review Coverage
Testing by people with no commercial relationship to us, which is a different kind of evidence from a laboratory result.
| Publication | Product | Finding |
|---|---|---|
| Business Insider, 2026 | TrueCarbon™ 200C | Top choice for removing odors, from a field of more than forty air purifiers tested |
| New York Times Wirecutter | AirMend™ Small Room | Measured smoke reduction of 99% at highest fan speed and 96% at the fourth of seven speeds. |
| Modern Castle | Mod, Mod+, Mod Jr., AirMend, and the discontinued EJ120 | Five separate reviews using a laser particulate meter. |
| Clemson University, 2011 | Max, since discontinued | Independent agar-plate study of leading purifiers. The Max was the only unit producing completely clean plates. |
Editorial testing has its own limits. Sample sizes are small, methods vary between publications, and a favorable result is a snapshot rather than a certification. It is useful precisely because the tester has no stake in the outcome.
Every independent review we know about, including the criticisms, is collected on our air purifier reviews page with links to the originals.
Frequently Asked Questions
What is CADR and who verifies it?
CADR, or Clean Air Delivery Rate, measures how much filtered air a purifier delivers per minute, in cubic feet per minute. It is tested separately for smoke, dust and pollen particles. The program is run by AHAM and testing is carried out by independent laboratories such as Intertek, with certified products randomly retested. Verified results are published in a public directory at ahamverifide.org, which anyone can search.
Is there a CADR equivalent for odors and gases?
Yes. AHAM AC-4-2022 is a certification covering chemical gas reduction, tested by independent laboratories, so a standard does exist. Two things limit it: participation is optional, so most purifiers advertising carbon filtration have never been tested against it, and there is no public verified directory, so a result cannot be looked up the way a CADR can. Carbon weight and bed depth remain the specifications you can verify for yourself.
Will air purifier room size claims be regulated?
Possibly. The FTC is currently reviewing whether to regulate coverage claims for air purifiers, which are unregulated today and vary widely depending on the air change rate a manufacturer chooses to assume. If a rule is issued, the expectation is that it will be based on AHAM AC-1 for particles. That would make coverage figures directly comparable between brands for the first time.
What does ENERGY STAR mean for an air purifier?
It certifies energy efficiency, measured as CADR delivered per watt consumed at maximum speed. It is a voluntary program, and its criteria were raised significantly in October 2025, so the majority of air purifiers on the market no longer qualify. It measures efficiency rather than cleaning performance, so an efficient but weak purifier can still qualify. Administration is transitioning from the EPA to the Department of Energy.
What does CADR not tell me?
It is measured at maximum fan speed with a new filter, so it describes the machine on day one at its loudest setting. It says nothing about noise, gas and odor removal, ozone emission, energy use, or how performance holds up as the filter loads. A purifier can carry an excellent CADR and be unusable at the speed needed to deliver it.
Why do air purifier room sizes vary so much between brands?
Because coverage depends on the air change rate assumed, and brands may not state it. We show coverage at 4.8 air changes per hour for HEPA media air purifiers, which is the AHAM standard and equates to filtering all the air in the rated space every 12.5 minutes. When comparing purifiers, check that both coverage figures use the same air change rate, and if a brand does not say, assume the more flattering one.
What does CARB certification mean?
The California Air Resources Board requires air cleaners sold in the state to be tested and confirmed to emit ozone below a set limit. It is a safety certification rather than a performance one, and it says nothing about how well a purifier cleans. The certified device list is public. A device absent from it has not been tested against that limit.
How can I verify a manufacturer's performance claims?
Search the AHAM Verifide directory for the CADR, and the CARB certified device list for ozone. For gas and odor claims, ask which laboratory ran the test and against which method, then ask how many pounds of carbon the filter contains.
Who is AHAM and what is the Air Cleaners Council?
The Association of Home Appliance Manufacturers develops and administers the test standards used across the home appliance industry, including AC-1 for air cleaner CADR. The Air Cleaners Council is the group within AHAM that oversees air cleaning standards. Oransi founder Peter Mann chairs it, which is a reason to hold Oransi to these standards rather than a reason to take its claims on trust.
