Abstract: An air purifier having a side-access or horizontally-removable air filter assembly may include a housing, a base plate, a filter plate, a filter, and an air blowing unit. In some configurations the air purifier also includes a UV-light source and a removable covering or panel. Once the removable cover is separated from the housing, the filter plate with the filter assembly may be slid horizontally into and out of the housing. Once the filter plate, filter, and UV-light source are removed from the housing, the filter may be replaced, cleaned, and/or inspected.