No person shall cause or allow the emission of gases containing carbon monoxide into the atmosphere from any cupola with a manufacturer's rated melt rate in excess of 5 tons per hour, unless such gases are burned in a direct flame afterburner so that the resulting concentration of carbon monoxide in such gases is less than or equal to 200 ppm corrected to 50 percent excess air or such gas streams are controlled by other equivalent pollution control equipment approved by the Agency according to the provisions of 35 Ill. Adm. Code 201.
Ill. Admin. Code tit. 35, § 216.381