Products · Air purifiers · Dyson
Dyson Purifier Big+Quiet Formaldehyde BP04
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Dyson’s largest purifier: CARB lists it as mechanical and Dyson calls it fully sealed. Dyson publishes no CADR, room rating or noise figure, and its two filter lives disagree. We are asking for a CADR and test reports. About $1,200.
Best for A buyer who wants Dyson’s design and its catalytic formaldehyde filter and accepts that we cannot check how big a room it suits.
- Our quality rating
- Fair (3 of 5)
- Price range
- Premium
- Verified marks
- Listed by CARB as a mechanical air cleaner (BP04 YY and BP04 ZZ)
- Size
- Floor unit, 26.2 lb, 32.7 in tall; Dyson’s US page gives no room rating or CADR
approx. $1,200
See it on Dyson’s site →We are not affiliated with Dyson. This link goes to the maker’s own page, with no tracking code. How we're funded.
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How we evaluated it
Why we chose it What put it on our list
- CARB lists the BP04 (variants YY and ZZ) as Mechanical (notified 2023-05-10, order G-23-113). By CARB’s definition that means filtration only, with no ozone or ions.
- Dyson says a HEPA H13-grade filter, a K-carbon filter and a permanent catalytic filter work inside a fully sealed machine, and that the HEPA stage captures 99.97% of particles as small as 0.1 microns. It names no lab for that figure.
- Dyson says a third party tested the whole machine for formaldehyde, based on GB/T 18801-2022. It does not name the lab or publish the result.
- Parts and prices are published: HEPA filter $169.99 (replace every 5 years), K-carbon filter $109.99 (every 2 years), remote $29.99. That is about $89 a year if you follow Dyson’s intervals. The machine has a 2-year limited warranty.
Trade-offs What to weigh before you buy
- Dyson’s US page gives no CADR, no room rating and no decibel figure. It says only that PM2.5 purification was tested in a large chamber by Dyson’s own methods, and that the machine projects air over 32 feet. AHAM’s directory has no Dyson entry, so we cannot apply the two-thirds room rule.
- Dyson’s filter lives conflict. The product page says the HEPA filter lasts up to 11 years. The parts listing says to replace it every 5 years or when the app says so.
- It costs about $1,200. Not every Dyson purifier is filtration only: CARB lists several purifier-humidifier models (for example PH05 and PH4A) as Electronic.
- Dyson’s page makes claims about viruses, bacteria and formaldehyde. See what trials show about air purifiers.
What to know Details worth knowing first
The Big+Quiet is Dyson’s most capable purifier on paper: a HEPA filter, a carbon filter and a catalytic filter for formaldehyde, all inside a casing Dyson calls fully sealed. CARB files the BP04 as a mechanical cleaner, which is what our air purifier guide looks for.
The trouble is what Dyson leaves out. It publishes no CADR, room rating or decibel figure, so there is no way to check the room size against our two-thirds rule or to judge the noise. Its filter lives also disagree with each other, and the HEPA and formaldehyde tests are Dyson’s, from labs it does not name. For formaldehyde in general, see formaldehyde.
At about $1,200 it costs far more than models that publish a verified CADR. It may suit you if you already like Dyson’s design. We are asking Dyson for a CADR and its test reports; until they arrive, we cannot tell you what size of room it suits. If that matters to you, choose a model with a listed CADR.
Quality & testing How it measures up against our checklist
- Tested by
- CARB (listing)
| What we checked | What we found |
|---|---|
| True HEPA Maker’s claim | Dyson says the filter is HEPA H13 grade and captures 99.97% of particles as small as 0.1 microns. The only test it describes is for filter life (DEHS oil as in EN 1822, in a chamber built to ASTM F3150). No lab, no report. |
| No ozone (CARB listing) Verified | CARB’s list has Dyson BP04 YY and BP04 ZZ as type Mechanical, notified 2023-05-10, order G-23-113. |
| Right size (CADR) Not verified | No CADR or room rating on Dyson’s US page. No Dyson entry in AHAM’s directory (searched 2026-10-22). |
| Carbon for gases Maker’s claim | A K-carbon filter (potassium carbonate, rated 2 years) and a permanent catalytic filter for formaldehyde, per Dyson. The amount of carbon and the formaldehyde result are not published. |
| Running cost and noise Not verified | Dyson publishes HEPA $169.99 and K-carbon $109.99 with change intervals. It gives a night mode noise comparison but no decibel figure. |
What the labels mean
- Verified We opened an independent record that confirms it: a certifier’s listing, a regulator’s list or a lab report. It is linked under Sources.
- Maker’s claim The maker says so on its own page or label. We read it but found no independent record.
- Not verified We looked and could not confirm it, or the maker does not say. Treat it as unknown.
Sources Where our facts come from
- Dyson Purifier Big+Quiet Formaldehyde BP04 product page. Maker’s page. Price, specifications, filter prices and footnotes as seen on 2026-10-22. Opens in a normal browser; dyson.com blocks automated fetches. Open ↗
- CARB list of certified air cleaning devices (search for Dyson). Certifier or regulator listing. BP04 YY and ZZ are type Mechanical (order G-23-113). The list is one long table with no link for a single model. Open ↗
- AHAM Verifide directory (search for Dyson, BP04). Certifier or regulator listing. A search tool with no link for a single listing. Searches for Dyson, BP04 and Big+Quiet returned no listing on 2026-10-22. Open ↗
- The Dyson Limited Warranty. Maker’s page. Lists a 2-year limited warranty for purifiers and humidifiers and for cordless vacuums. Open ↗
Alternatives Other options to compare
- IQAir HealthPro Plus XE About $1,200, with a separate carbon cartridge and published filter prices. It also publishes no CADR.
- Levoit Eleva 500X About $260, with an AHAM-listed smoke CADR of 301 and a CARB mechanical listing. It is new: Amazon lists it as first available on 2026-10-18.
- Oransi Mod+ About $699, with an AHAM smoke CADR of 363 and a HEPA and carbon filter in one.