If you source air purifiers from China to sell overseas, CADR (Clean Air Delivery Rate) is the single most important performance number in this category — but the number itself has several exploitable gaps, plus a built-in blind spot in the international standard behind it. This guide covers specific verification methods, and why “meeting the CADR claim” isn’t the same as “still meeting it a few months later.”
1. The three CADR numbers should be close together — a big gap is a signal
The AHAM (Association of Home Appliance Manufacturers) CADR standard breaks purification performance into three independent numbers: smoke, dust, and pollen. A well-designed HEPA purifier should have these numbers reasonably close together (usually within 10-20 of each other). Smoke particles are the finest and hardest to filter — if a purifier’s smoke CADR is noticeably lower than its dust and pollen CADR, that indicates the airflow or filter design can’t keep up with fine-particle removal, even if the overall CADR figure quoted doesn’t look bad. Fine particles are also often the ones with the greatest health impact, so this is where the claim is most likely to overstate real-world capability.
How to verify: require the supplier to provide all three independent numbers, not a single generic “CADR XXX,” and check whether they’re reasonably close together.
2. A common unit trick: using m³/h instead of CFM to make the number look bigger
Some manufacturers selling into North America label airflow in m³/h (cubic meters per hour) instead of the standard CFM (cubic feet per minute) — the conversion ratio isn’t 1:1, and using m³/h makes the same real performance look substantially bigger, for example, 235 CFM converts to roughly 400 m³/h — the identical real capability, but the number appears roughly 70% higher just by switching units. The fix is simple: for any number you receive, first confirm whether it’s CFM or m³/h, convert both to the same unit before comparing, and don’t let the choice of unit itself mislead you.
3. “Meets the CADR claim” and “how long it lasts” are two different things — a known limitation of the CADR standard itself
Even testing organizations acknowledge this openly: AHAM’s CADR test runs for only 20 minutes (10 minutes for pollen), using a brand-new filter — it measures “instantaneous performance in pristine condition,” not whether that efficiency holds up after months of use. Independent testing organizations have documented purifiers losing 50% of their efficiency after just 8 weeks of use. This isn’t fraud — it’s a genuine methodological gap in the CADR standard itself, affecting every brand to varying degrees, with degradation speed being the real differentiator.
China’s own national standard, GB/T 18801-2022, addresses this gap specifically — adding CCM (Cumulative Clean Mass), a metric AHAM’s standard doesn’t have, graded P1-P4 for particulates and F1-F4 for formaldehyde, with a higher grade indicating longer filter life.
How to verify: in addition to CADR, separately request CCM grade data from the supplier — CADR tells you “how fast it cleans when new”; CCM tells you “how long that performance actually lasts.” You need both for a complete picture.
4. Real, documented ways manufacturers “manufacture” impressive lab numbers
A recent Chinese industry media comparison test explicitly documented the specific tactics: some brands use a low-concentration test environment, shorten the test duration, and use a brand-new, unused filter to produce an “instant high score” — figures that look good under lab conditions but drop significantly once real household conditions apply (furniture obstructing airflow, continuous pollution sources, gradual filter wear). The real test data from that comparison also provides a useful reference range: actual measured formaldehyde CADR among mainstream models ranged from as low as 240 m³/h to over 800 m³/h — a gap of more than 3x — showing genuine real-world performance varies significantly within this category, and the marketing number alone doesn’t tell you where a given product falls.
How to verify: require the supplier to provide the CMA/CNAS-certified test report number (not just a document), and where possible, verify that the data behind that specific report number matches the claimed figure — this is an independently checkable step, more reliable than accepting a PDF at face value.
5. “HEPA” labeling has its own trap, and it’s not the same as “True HEPA”
The word “HEPA” itself carries no mandatory testing or labeling oversight in many markets — “True HEPA” generally refers to a tested filter capturing 99.97% of 0.3-micron particles; but terms like “HEPA-type,” “HEPA-like,” “HEPA-style,” or “99% HEPA” are marketing language with no standardized test backing them, and their actual efficiency can be significantly lower than true HEPA. How to verify: require the supplier to specify the exact grade against the European EN1822 standard (such as H13 or H14), rather than accepting a generic “HEPA” label.
The bottom line
An air purifier’s CADR figure carries three separate points worth scrutinizing: consistency across the three individual numbers, unit-conversion tricks, and the “fresh out of the box vs. after real use” gap that’s a genuine limitation of the standard itself. The reliable way to verify: request all three independent CADR numbers instead of one generic figure, convert to a common unit before comparing, separately request CCM data for filter durability, ask for the CMA/CNAS test report number to check authenticity, and pin down “HEPA” to a specific EN1822 grade. Meeting the headline spec is just the entry ticket — whether it holds up after months of real use is the real test in this category.
Testing standards referenced (AHAM AC-1, EN1822:2009, China’s GB/T 18801-2022) reflect current industry practice as of 2026. Real-world performance range figures are drawn from independent comparison testing reported in industry media. Verify specific product claims and test report authenticity before making sourcing decisions. General guidance, not legal advice.