NestyFinds

Medify Air MA-40

By the NestyFinds editorial team · Researched from manufacturer documentation, manuals and the AHAM Verifide directory · not bench-tested · Reviewed:

Medify Air MA-40
370 ft² CADR 239 cfm AHAM Verifide CARB certified 46–66 dB

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.

Pros

  • The CADR is independently measured, not self-declared: AHAM Verifide at 239 cfm smoke, 231 dust and 240 pollen, with a 370 sq ft room size that reconciles exactly with AHAM's own 4.8 air-changes rule.
  • Medify states filter life in HOURS — 3,000 of them — which is the usage assumption every other brand on this site leaves out. It lets you work out your own calendar instead of trusting theirs: 3,000 divided by the hours you run it a day.
  • Its maintenance instruction comes with a reason rather than a rule. "Do not vacuum or try and wash filter as it will clog filter" tells you what happens if you do, which is more useful than a prohibition.

Cons

  • ⚠️ The device class changed between revisions of the same model name: CARB lists earlier MA-40s as Electronic and the V3.0 and V4.0 as Mechanical. You cannot tell which you are buying from the name alone.
  • ⚠️ Its quietest setting is 46 dB. That figure is not on medifyair.com — it is on Medify's own Amazon listing — and it is loud for a minimum: several units in this catalogue start in the low twenties. On a purifier meant to run continuously, this is the specification most likely to decide whether it stays switched on.
  • Medify publishes no wattage, dimensions or weight on the pages we read.
  • The filter is a single sealed cartridge with nothing washable, so the whole thing is the consumable and there is no maintenance that postpones it.
  • AHAM's directory does not mark this model as meeting ozone limits, while it does mark the MA-15 and MA-50. We do not know whether that is a data gap or a finding.

Our editorial rating, not a lab measurement. Weighed independent measurement above manufacturer claims, and the MA-40 scores well there: a full AHAM Verifide CADR set and a room size that reconciles with AHAM's own arithmetic. The hours-based filter interval counts in its favour too, because it is the one figure that makes a filter life comparable between two homes. Against it: no published noise or wattage, nothing washable in the filter, and a revision history in which CARB classifies some MA-40s as Electronic and others as Mechanical under one model name.

Verdict

The MA-40's case rests on evidence rather than marketing: AHAM measured it at 239 cfm smoke CADR and sized it at 370 sq ft, and that room figure reconciles exactly with AHAM's published 4.8-air-changes rule. Medify then does something almost no competitor does and states filter life in hours rather than months, which hands you the assumption instead of hiding it. Against that, the specification sheet is thin where it matters for daily use — no published noise figure, no wattage — and CARB's records show the same model name covering both Electronic and Mechanical revisions, so the machine you receive depends on a version code you have to read off the plate.

Check current price for the Medify Air MA-40 on Amazon (opens in a new tab)

Price, seller and package contents change. Check the variant on Amazon before you buy.

Is it the right one for you?

Who it's for

  • Anyone who wants an independently measured CADR rather than a brand's own number, in a room around 370 sq ft at AHAM's 4.8 air changes.
  • People who run a purifier intermittently and are tired of month-based filter intervals that assume continuous use. The hours figure is genuinely more honest.
  • Buyers willing to check the revision on the rating plate before ordering.

Who should skip it

  • Anyone who wants a quiet bedroom machine. At 46 dB on its lowest speed it is among the loudest minimums in this catalogue.
  • Anyone who wants smart features: there is no app, no voice control and no air-quality sensor documented for this model.
  • Anyone who specifically wants a purely mechanical machine and cannot check the revision before it arrives.

Specifications

How this coverage figure is stated

AHAM's own suggested room size, which is derived from the smoke CADR by AHAM's published rule (smoke CADR x 1.55) and therefore corresponds to 4.8 air changes per hour. 239 x 1.55 = 370, and the directory prints 370 — the arithmetic reconciles exactly. This is a third-party figure, not a manufacturer coverage claim.

Always compare two purifiers at the same air-change rate; manufacturers pick different ones and the headline square footage is not otherwise comparable.

Medify Air MA-40 — documented specifications
Smoke CADR 239 cfm, AHAM Verifide
AHAM suggested room size 370 sq ft (equivalent to 4.8 air changes per hour)
CARB, current revisions MA-40-V3.0 Mechanical (G-23-267); MA-40-V4.0 Mechanical (G-25-237)
Noise 46–66 dB across three fan speeds from Medify's own Amazon listing, NOT from medifyair.com, which publishes no figure
Filter life 3,000 hours of use Medify publishes hours, not months
Dust CADR 231 cfm, AHAM Verifide
The full record: 7 more documented specifications — nothing is removed, it is just not what decides
Pollen CADR 240 cfm, AHAM Verifide
PM2.5 CADR 235, AHAM Verifide
Filter stages Pre-filter, H13 HEPA, activated carbon
Filter indicator reset Hold the dimmer or filter button 3 to 5 seconds
Cleaning the filter "Do not vacuum or try and wash filter as it will clog filter"
CARB, earlier revisions MA-40 Electronic (G-21-461 and G-19-130)
Meets AHAM ozone limits Not marked in the directory for this model while it is marked for the MA-15 and MA-50
7 things we could not verify — we leave these blank rather than estimate them
  • ⚠️ THE AHAM COLUMN ORDER IS NOT THE ONE MOST SOURCES USE, and getting it wrong would have put the wrong number on this page. AHAM's directory prints DUST CADR first, then TOBACCO SMOKE, then POLLEN. We checked the printed table header and then confirmed it arithmetically: AHAM's own rule is room size = smoke CADR x 1.55, and 239 x 1.55 = 370, which is the room size printed. Taking the first column as smoke would have given 231 and a room size that does not reconcile.
  • THE NOISE FIGURE COMES FROM THE RETAIL LISTING, NOT THE MANUFACTURER'S SITE. medifyair.com publishes no decibel figure for this model; Medify's own Amazon listing states 46 dB minimum and 66 dB maximum across three fan speeds. It is the manufacturer speaking, but on a retail page rather than in its documentation, and it is labelled as such in the table.
  • THE AHAM EDITION WE READ IS OCTOBER 2023. A later certification or a re-rate would not appear in it. AHAM's live directory is a JavaScript application whose data we could not read directly.
  • NO NOISE FIGURE, WATTAGE, DIMENSIONS OR WEIGHT are published by Medify on the pages we read, so those fields are null rather than estimated.
  • MEDIFY PUBLISHES NO MONTH-BASED INTERVAL for this filter, only 3,000 hours, so filter_life_months is null on purpose. Converting it for you would reintroduce exactly the hidden assumption Medify avoided.
  • AHAM'S "MEET OZONE LIMITS" COLUMN IS BLANK FOR THE MA-40 while it reads Yes for the MA-15 and MA-50. We report the blank; we do not know whether it means untested, not applicable, or a gap in the directory.
  • THE CARB REVISION HISTORY IS REPORTED AS READ. We did not establish which revision any given retail listing ships, only that CARB records both Electronic and Mechanical MA-40s.

Our calculation, not the manufacturer’s

What 239 cfm of smoke CADR actually covers

Air changesWhen you want this rateRoom it suits
4.8×/hourWildfire smoke, allergy season, a room you are sensitive in373 ft²
4×/hourThe rate most allergy guidance assumes448 ft²
2×/hourGeneral freshening in a room without a specific problem896 ft²

Worked from the CDC/NIOSH relation air changes = (CADR × 60) ÷ (area × ceiling height), assuming an 8 ft ceiling. Change the ceiling height and these numbers change. AHAM’s own consumer rule — a smoke CADR of at least two-thirds of the room’s area — puts the ceiling for this unit at about 359 ft², which is the same arithmetic at roughly five air changes an hour.

You can check this at home. In a closed room of the size in the first row, PM2.5 should halve about every nine minutes at top speed once its source stops. A monitor shows whether this unit manages that in your home. How to run the test

Ionizer and ozone

⚠️ THIS IS THE THING TO CHECK BEFORE BUYING, AND IT IS NOT ON THE BOX. CARB has certified the MA-40 several times over, and the device class CHANGED between revisions. Read from CARB's complete certified list on 14-sep-2026:

· MEDIFY AIRx | MA-40 H13 Grade Air Purifier | MA-40 | ELECTRONIC | 2019-09-06 | G-19-130 · Medify Air | Air Purifier | MA-40 | ELECTRONIC | 2021-10-15 | G-21-461 · Medify Air | Air Purifier | MA-40UV | ELECTRONIC | 2021-11-04 | G-21-483 · Medify Air | Air Purifier | MA-40-V3.0 | MECHANICAL | 2023-10-03 | G-23-267 · Medify Air | Air Purifier | MA-40-V4.0 | MECHANICAL | 2025-09-10 | G-25-237

Under California's regime only ELECTRONIC air cleaners are tested against the ozone emission limit, because only they have a component capable of generating it. A Mechanical classification means CARB did not identify one. So the earlier MA-40 revisions carried something the V3.0 and V4.0 do not.

What that means for a buyer: the model name alone does not tell you which you are getting. HOW TO CHECK: read the revision on the rating plate and on the packaging. A plate reading MA-40-V3.0 or MA-40-V4.0 is the Mechanical revision. A plate reading plain MA-40 is one of the Electronic ones. The MA-40UV is a separate, explicitly UV-equipped product and is not the same machine.

What you actually get

What the linked package includes
Capability What it needs Status
Particle filtration H13 HEPA stage, included Included
Odour and gas reduction Activated carbon layer, part of the same cartridge Included
Replacement filter MA-40 Filter, sold separately Sold separately
Air-quality sensor Not documented for this model Not verified
App or voice control Not documented for this model Not verified
Published noise figure Not published by Medify Not verified

Package contents vary by variant and seller. Check what is in the box on the Amazon listing before you buy. “Not verified” means the manufacturer does not document it either way — not that it is missing. “Not offered” is the other thing: the manufacturer does document it, and the answer is that this model does not have it.

Replacement filter

Full filter guide

Medify MA-40 replacement filter

Part "MA-40 Filter" · 3,000 hours of use, per Medify's own FAQ. Not months — hours. That is worth dwelling on, because it is the opposite of how every other brand on this site publishes. A month-based interval hides the assumption that makes it meaningful: run a unit four hours a day and 3,000 hours is roughly two years; run it around the clock and it is about four months. Same filter, same number, wildly different calendars — and Medify is letting you do that arithmetic instead of doing it for you and hiding the inputs. Run it yourself: 3,000 divided by the hours you run the unit each day gives you the days. ⚠️ The figure is per model and not uniform: Medify states 3,000 hours for the MA-18, MA-25, MA-35 and MA-40, and 2,500 hours for the MA-50.

Which filter fits

How we researched this

Checked against the AHAM Verifide directory, CARB's certified air-cleaner list and the manufacturer's own pages. We did not test this unit. Nothing here is a measurement of ours: every figure is either documented by the manufacturer or published by an independent standards or testing body, and where the two disagree this page says so.

Not verified for this model — 7 notes
  • ⚠️ THE AHAM COLUMN ORDER IS NOT THE ONE MOST SOURCES USE, and getting it wrong would have put the wrong number on this page. AHAM's directory prints DUST CADR first, then TOBACCO SMOKE, then POLLEN. We checked the printed table header and then confirmed it arithmetically: AHAM's own rule is room size = smoke CADR x 1.55, and 239 x 1.55 = 370, which is the room size printed. Taking the first column as smoke would have given 231 and a room size that does not reconcile.
  • THE NOISE FIGURE COMES FROM THE RETAIL LISTING, NOT THE MANUFACTURER'S SITE. medifyair.com publishes no decibel figure for this model; Medify's own Amazon listing states 46 dB minimum and 66 dB maximum across three fan speeds. It is the manufacturer speaking, but on a retail page rather than in its documentation, and it is labelled as such in the table.
  • THE AHAM EDITION WE READ IS OCTOBER 2023. A later certification or a re-rate would not appear in it. AHAM's live directory is a JavaScript application whose data we could not read directly.
  • NO NOISE FIGURE, WATTAGE, DIMENSIONS OR WEIGHT are published by Medify on the pages we read, so those fields are null rather than estimated.
  • MEDIFY PUBLISHES NO MONTH-BASED INTERVAL for this filter, only 3,000 hours, so filter_life_months is null on purpose. Converting it for you would reintroduce exactly the hidden assumption Medify avoided.
  • AHAM'S "MEET OZONE LIMITS" COLUMN IS BLANK FOR THE MA-40 while it reads Yes for the MA-15 and MA-50. We report the blank; we do not know whether it means untested, not applicable, or a gap in the directory.
  • THE CARB REVISION HISTORY IS REPORTED AS READ. We did not establish which revision any given retail listing ships, only that CARB records both Electronic and Mechanical MA-40s.

Sources consulted

Other purifiers we have researched

All reviews