DESC: The Allerair 5000 D Air Purifier is designed for situations where significant levels of airborne chemicals, gases, odors or mold spores are present. This air purifier features an extra-deep 22 lbs. carbon bed, which increases dwell time, allowing more chemicals, gases and odors to be absorbed. The 5000 D provides approximately one and a half times the gas and odor filtration of the 5000 Exec model.