Blueair Blue Signature moves more air (CADR) and covers a larger room than KNKA APH4000.
Which purifier has higher CADR?
Blueair Blue Signature has higher CADR (455 vs 226 CFM).
Which purifier is quieter?
KNKA APH4000 is quieter (22 vs 23 dB).
Which purifier covers a larger room?
Blueair Blue Signature fits a larger room (about 705 vs 350 sq ft recommended from CADR).
Which purifier has better smart features?
Blueair Blue Signature lists Wi-Fi or app control; KNKA APH4000 does not.
Which purifier has longer filter life?
Blueair Blue Signature lists a replacement interval of 179.99; KNKA APH4000 does not.
Bottom line
Blueair Blue Signature moves more air (CADR) and covers a larger room than KNKA APH4000.
| Metric | Blueair Blue Signature | KNKA APH4000 |
|---|---|---|
| CADR (smoke) | 455 CFM | 226 CFM |
| Recommended room size | 705 sq ft | 350 sq ft |
| Claimed coverage | 3385 sq ft | 1695 sq ft |
| Noise | 23 dB | 22 dB |
| Filter type | HEPASilent | HEPA |
| Filter interval | 179.99 | — |
| Smart features | None | None |