Dyson
Dyson Purifier Big+Quiet Formaldehyde BP04
$929.99
Released 2023
Best Air Purifiers · head-to-head
Dyson Purifier Big+Quiet Formaldehyde BP04 vs Alen BreatheSmart 75i
A sourced, side-by-side comparison. Alen BreatheSmart 75i is cheaper at $799. Every spec and price links to its source.
Alen
Alen BreatheSmart 75i
$799Cheaper
Which is better: the Dyson Purifier Big+Quiet Formaldehyde BP04 or Alen BreatheSmart 75i?
On the specs we track, they're closely matched. The Alen BreatheSmart 75i is the cheaper at $799.
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Full spec sheet
✓ marks the stronger figure where "more" — or "less", for price and weight — is unambiguously better.
| Spec | Dyson Purifier Big+Quiet Formaldehyde BP04 | Alen BreatheSmart 75i |
|---|---|---|
| US price | $929.99 | $799 |
| Brand | Dyson | Alen |
| Released | 2023 | — |
| Cadr smoke (CFM) | — | — |
| Coverage (sq ft) | — | 1400 |
| Hepa | Yes | Yes |
| Filter type | 360° HEPA H13 + K-Carbon filter + SCO (Selective Catalytic Oxidization) formaldehyde filter | Advanced Particle filter + Medical-grade True HEPA (H13) + Ionizer (switchable); optional Carbon layer (Fresh/Ultimate filters) |
| Noise db min | — | 25 |
| Smart | Yes | Yes |
| Energy star | No | Yes |
| Release | 2023 | — |
Sources — Dyson Purifier Big+Quiet Formaldehyde BP04: dyson.com (verified 2026-06-15). Alen BreatheSmart 75i: alen.com (verified 2026-07-07).
What's the difference between the Dyson Purifier Big+Quiet Formaldehyde BP04 and Alen BreatheSmart 75i?
Where the two actually differ on the specs we track (2 of 7). Matching specs are omitted.
- Filter type: Dyson Purifier Big+Quiet Formaldehyde BP04 360° HEPA H13 + K-Carbon filter + SCO (Selective Catalytic Oxidization) formaldehyde filter vs Alen BreatheSmart 75i Advanced Particle filter + Medical-grade True HEPA (H13) + Ionizer (switchable); optional Carbon layer (Fresh/Ultimate filters)
- Energy star: Dyson Purifier Big+Quiet Formaldehyde BP04 false vs Alen BreatheSmart 75i true
What reviewers say
Sourced tester consensus for each — the "what people who used it think" layer, not just specs.
Dyson Purifier Big+Quiet Formaldehyde BP04
Three whitelisted outlets (TechRadar, Reviewed/USA Today, TechHive) hands-on or lab tested the Dyson Purifier Big+Quiet Formaldehyde; TechRadar and Reviewed covered the higher CO2-sensor trim (aligned with BP04) while TechHive tested the base Formaldehyde unit. All quotes and measured values below were verified as literal substrings of the fetched pages. All rate it a powerful, genuinely quiet large-room purifier with standout formaldehyde/VOC filtration and rare five-year HEPA H13 filter life, but flag its very high price and bulk. Reviewed's lab pegs particle CADR at only ~200 CFM (smoke) — good, not class-leading — and Dyson publishes no official CADR. (3 sourced reviews, 3 lab-tested.)
Praised: Best-in-class formaldehyde/VOC chemical filtration; Powerful; cleans very large open-plan spaces; Acoustically quiet despite its power.
Flagged: Very expensive; costs a small fortune; Big, heavy and bulky (26 lbs, ~33 in tall); Produces a strong, physically noticeable airflow/wind nearby.
Alen BreatheSmart 75i
Two whitelisted hands-on reviews (TechHive 2023, TechRadar 2024) cover this exact model. Both are qualitative with no lab-measured numbers. Both praise the powerful airflow for very large rooms (up to ~1,300 sq ft), the swappable colored front panels, and simple onboard controls that work without the app. Both flag the high price, being overkill for small spaces, loud higher/auto fan speeds, bulk, and an app that is hard to find or unintuitive. They split sharply on setup and framing. (2 sourced reviews.)
Praised: Powerful airflow suited to very large rooms (up to ~1,300 sq ft); Swappable colored front panels to match decor; Simple onboard controls, usable without the app.
Flagged: Very expensive and overkill for small spaces; Gets loud at higher/auto fan speeds; Large, bulky footprint.