No person may cause, allow or permit the installation or use of any article, machine, equipment, process or method which conceals an emission which would otherwise constitute a violation of an applicable rule. Concealment includes, but is not limited to, the use of gaseous diluents to achieve compliance and the unnecessary separation of an operation into parts to avoid coverage by a rule that applies only to operations larger than a specified size.
Wis. Admin. Code Department of Natural Resources NR 439.10