Automatic Filter Replacement Program - Join our Filter Replacement Program today and receive your Blueair SmokeStop™ filters delivered directly to you. It’s easy to do: just choose when you want to receive them and you can stop at any time! Plus enjoy Free Shipping on all your SmokeStop™ filters, always! Replacement SmokeStop™ filters for the Blueair Pro L air purifiers. A combination particle and carbon filter, the Pro L SmokeStop™ Filter is recommended for rooms with heavy gaseous pollutants, such as volatile organic compounds (VOCs) and cigarette smoke. Includes 2 SmokeStop V-shaped polypropylene filters for removing pollutants such as dust, pollen, bacteria, virus, pet dander, mold spores and other airborne particles down to 0.1 micron in size. Since polypropylene fibers are waterproof, Blueair purification systems do not require the use of chemical-based bacteriostats or mold inhibitors. Instead of absorbing the moisture in which bacteria thrive, polypropylene repels water and naturally prevents bacteria, mold and mildew from reproducing inside the filter. Replace filter every 6 months. Available auto-replacement shipment intervals are 4, 6 or 8 months.