A built-in apparatus and method for treating air including a housing with an air inlet and an air outlet. An air mover positioned near the air outlet is configured to draw the air through the air inlet. The housing encloses an air treatment zone, such as including an oxidizing zone, and an ozone removal zone positioned downstream of the air treatment zone and oxidizing zone. The air treatment zone includes UV light and/or ozone that partially oxidizes the chemical contaminants in the air treatment zone. A catalyst in the oxidizing zone oxidizes elements within the air treatment zone. The ozone removal zone includes a second, different catalyst material. A UV bulb that may or may not generate ozone is positioned within or downstream of the first and/or second catalyst materials to assist catalyst oxidation and/or self-clean the apparatus.