No person shall cause, suffer, allow or permit particles to be emitted from any stack or chimney into the outdoor air, the shade or appearance of which is greater than twenty-percent opacity, exclusive of water vapor.
The provisions of this article shall not apply:
A. 
To the emission of particles the shade or appearance of which is greater than twenty-percent opacity, exclusive of water vapor, for a period of not longer than three minutes in any consecutive thirty-minute period.
B. 
To source operations issued a variance in accordance with Chapter 7, Section 5, of the State Air Pollution Control Code.
C. 
To indirect heat exchangers.
D. 
To incinerators.
E. 
For a period of five years from the date of issuance of a valid permanent certificate to operate to a source operation equipped with control apparatus for which a valid permit to construct or the permanent certificate to operate was issued by the State Department of Environmental Protection during the period from June 15, 1967 to the effective date of this article.