Va. Code Ann. § 40.1-51.33

Any information, except emissions data, reported to or otherwise obtained by the Commissioner which contains or might reveal a trade secret shall be confidential and shall be limited to those persons who need such information for purposes of enforcement of this chapter or the federal Clean Air Act or regulations and orders of the Commissioner. It shall be the duty of each owner to notify the Commissioner of the existence of trade secrets when he desires the protection provided herein.