The Blue Pure 211+ Series SmokeBlock Replacement Filter is the ultimate tool against wildfire season. Additional activated carbon removes 99.99% of wildfire smoke along with extra protection against other wildfire emissions such as toxic gasses, smog and odors while also eliminating harmful gaseous pollutants such as volatile organic compounds (VOCs). In addition, advanced polypropylene filter media removes particle pollutants down to 0.1 micron in size from your indoor air, such as pollen, dust, and pet dander. Using a 360-degree air intake and up to 4 times the filter surface area vs. the same models with only mechanical filtration (H13 filter), the Blue Pure 211+ Series SmokeBlock filter lasts longer, on average 6 months. Subscribe & save up to 10% on auto-delivered filters when replacement is needed; We recommend replacing your filter about every 6 months depending on usage. ULTIMATE TOOL AGAINST WILDFIRE SEASON: 99.99% wildfire smoke removal based on removal testing of particles 0.4-0.7um in 60min in a 30m3 room. Performance may vary. Also tested on benzene, toluene, nitrogen oxide, sulfur dioxide. FILTERS BUILT TO LAST: Blueair models with HEPASilent's mechanical and electrostatic filtration produced higher CADR, lower noise, and had lower energy consumption vs. the same models with only mechanical filtration (H13 filter). *Tested on E.coli, Influenza A (H1N1), A.niger with a minimum reduction rate of 99.9% in 60min