Blue Pure 411i Max HEPASilent™ smart air purifier quickly cleans up to 526sqft living space in 30min or 219sqft in about 12.5min on high. Independently evaluated for safety standards and third-party tested for performance as part of the AHAM Verifide® Program for air cleaners, this air purifier has a Clean Air Delivery Rate (CADR) of 141 for fine smoke particles, dust and pollen. Get more out of the filter thanks to our proprietary RealTrack algorithm where fan speed, usage time and pollution levels are used to calculate exactly how dirty the filter is based on actual usage and tells you more accurately when to replace it within 9 months. Shop genuine Blueair Blue Pure F4MAX replacement filter designed for optimal performance: Blue Pure 411i Max air purifier replacement filter B08KPJQBQT. Blueair is the only line of air purifiers with a customizable, washable fabric pre-filter. Inspired by the latest Scandinavian design trend, Blue Pure Max air purifiers arrive in the Stockholm Fog pre-filter, while Limestone, Moss and Sand pre-filters are sold separately. *Comparing pollen CADR on high fan speed (Blue Pure 411a Max & 411i Max vs. Blue 411 Auto), other units may vary. Based on AHAM maximum allowable certified rating which may vary from the AHAM seal claimed valued. Noise refers to the dB(A) difference in acoustic power. **When similar CADR was measured, Blueair models with mechanical and electrostatic filtration achieved less noise with less energy than same models with only H13 HEPA mechanical filtration. ***Tested PM 2.5 (0.1 - 2.5 microns) up to 90min in a 30m3 room. Tested to remove min. 99.9% of S. aureus, K. pneumoniae, P. aeruginosa, MS2, E.Coli, H1N1, A.Niger.