This high-performance PD 20L Activated Carbon Replacement Filter removes odors, smoke, chemicals, and more from the air entering the dehumidifier. Essential for those suffering from allergies and asthma. This filter is laboratory tested to retain 99.97% of harmful airborne microparticles, bacteria, germs, and pollutants. The filter should be changed every 3-4 months depending on the pollutants in the application area. It can ensure up to annual use. You should be particularly careful regarding the maintenance of the filter. It should be cleaned every five days.