What to know about Blueair Blue Signature Large (SP4i)
Why it stands out
Why we like it
It suits a large primary bedroom where a smaller unit would have to run louder.
What to know
Score breakdown
Independently measured noise on low or sleep speeds (HouseFresh, Tom's Guide, RTINGS) and how much clean air the unit delivers at a sleep-tolerable level, roughly 45 dB or less. Brand dB claims count for less.
AHAM CADR and 4.8 ACH room rating versus a typical 150–400 sq ft bedroom, plus independent smoke and particle test results.
Dedicated sleep or night mode, display that turns off or dims via a light sensor, no light leakage or beeps, auto mode that doesn't ramp up abruptly overnight, timer.
No ionizer, or one that can be switched off; CARB or zero-ozone verification; true mechanical HEPA versus electrostatic filtration; recalls or labelling disputes.
Annual filter cost, filter life, energy use, availability of genuine filters, warranty.
Street price relative to quiet cleaning delivered for a bedroom.
Blueair Blue Signature Large (SP4i) specs
Noise
- Lowest-speed noise (manufacturer)
- 23 dB
- Top-speed noise (manufacturer)
- 55 dB
- Lowest-speed noise (independent measurement)
- 34.8 dBA
Performance
- CADR (smoke where given, else headline)
- 455 cfm
- Recommended room size (4.8–5 ACH / AHAM)
- 705 sq ft
Sleep features
- Sleep / night mode
- Yes
- App control
- Yes
Health & materials
- Ionizer / electrostatic stage
- Ionizer that cannot be disabled (per HouseFresh)
- Filter type
- 7-stage filter incl. pelleted carbon
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Prices and availability may change. The retailer's price and availability at checkout govern the transaction.
| Retailer | Price | Availability | |
|---|---|---|---|
| AmazonLowest | $439.99 $449.99 | In Stock | View deal |
Based on 2 retailer price observations captured during the last 90 days.