The Dual Filter is a combination of a HEPA H12 filter and an activated carbon filter. The H12 HEPA filter removes pollutants such as animal hair, fine dust, pollen, viruses and bacteria from the air while the activated carbon filter adsorbs gases - unpleasant odours, tobacco smoke, volatile organiccompounds, etc. Compared to an H14 HEPA filter, the H12 HEPA filter is not as dense which meansthat it can filter more air over the same period of time. The Dual Filter will need to be replaced every8-12 months