9 Va. Admin. Code § 5-20-70
A. No owner or other person shall cause or permit the installation or use of any device or any means which, without resulting in reduction in the total amount of air pollutants emitted, conceals or dilutes an emission of air pollutants which would otherwise violate this chapter. Such concealment includes, but is not limited to, either of the following:
§§ 10.1-1307 and 10.1-1308 of the Code of Virginia.
Derived from VR120-02-07, eff. January 1, 1985.