Blueair Particle Replacement filter for the Blue Pure Fan. Unlike standard fans, the filter + fan combination removes over 99% of large airborne particles, like pollen and dust in just 20 minutes⁰ to deliver air that's both cooling and clean. This filter is 100% recyclable and naturally antibacterial, so the only thing you’re adding back into the environment is fresh air. For optimal performance, use genuine Blueair filters and replace the filter about once every six months when used 24 hours a day. The use of non-genuine filters will void the warranty. ⁰Based on third-party testing of removal rate of dust particles (2.839μm) and pollen particles (7.234µm) in 20 minutes at a room volume of 1,008 ft³ according to AHAM AC-1-2019 standard.