No person may permit the use of a device, stack height which exceeds good engineering practice stack height, dispersion technique or other technique which, without resulting in reduction of the total amount of air contaminants emitted, conceals or dilutes an emission of air contaminants which would otherwise be in violation of this article, except that with prior approval of the Department, the device or technique may be used for control of malodors.
25 Pa. Code § 121.9