An electrophotographic apparatus includes a photoconductor; a charging device for placing a uniform charge on the photoconductor; an image writer for writing an image on the charged photoconductor; a developer station for developing the image with toner; a transfer station for transferring the toned image to a receiver; a fixing unit for fusing the image to the receiver; environmental control system for removing airborne contaminants from the electrophotographic apparatus; the environmental control system includes a catalytic filter; and ozone is added prior to the catalytic filter when the contaminant is formaldehyde.