Blueair offer two types of filters for most of their air purifiers - HEPASilent and SmokeStop. The HEPASilent filter uses a pleated design that when combined with air purifier creates filtration rates that exceed the HEPA standard. SmokeStop filters take this same HEPASilent particle filtration and add in granulated, activated carbon to adsorb odors, break down VOCs, and remove odors. The Blueair filters even fit older models. At any time you can switch from HEPASilent to SmokeStop and vice versa. Replace your Blueair air purifier filter every six months. If you have an ECO10, replace your filters annually.