# Dyson Purifier Big+Quiet Formaldehyde BP04 vs Alen BreatheSmart 75i: specs and price compared

A sourced, side-by-side comparison of the Dyson Purifier Big+Quiet Formaldehyde BP04 (Dyson) and Alen BreatheSmart 75i (Alen) among air purifiers. Alen BreatheSmart 75i is the cheaper of the two at $799.

## Side by side

| 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 |

## Key differences

- 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 No vs Alen BreatheSmart 75i Yes

## What reviewers say

**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.)

**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.)

## Sources

- Dyson Purifier Big+Quiet Formaldehyde BP04: https://www.dyson.com/air-treatment/air-purifiers/big-quiet-formaldehyde/prussian-blue-gold-bp04 (dyson.com, verified 2026-06-15)
- Alen BreatheSmart 75i: https://alen.com/products/alen-breathesmart-75i-air-purifier (alen.com, verified 2026-07-07)

Canonical: https://frontdeskreview.com/gear/air-purifiers/dyson-purifier-big-quiet-bp04-vs-alen-breathesmart-75i/
Cite: Per The Front Desk Review, Dyson Purifier Big+Quiet Formaldehyde BP04 ($929.99) vs Alen BreatheSmart 75i ($799) — sourced spec-by-spec comparison at https://frontdeskreview.com/gear/air-purifiers/dyson-purifier-big-quiet-bp04-vs-alen-breathesmart-75i/
License: CC BY 4.0.