Ill. Admin. Code tit. 35, § 217.301 – Industrial Processes

a) New Industrial Processes. No person shall cause or allow the emission of nitrogen oxides into the atmosphere from any new process producing products of organic nitrations and/or oxidations using nitric acid to exceed the following standards and limitations:
1. 1) 2.5 kg of nitrogen oxides (expressed as nitrogen dioxide) per metric tonne of nitric acid (100 percent acid basis) used in such new process (5.0 lbs/T).
2. 2) Visible emissions in excess of 5 percent opacity.
b) Existing Industrial Processes. No person shall cause or allow the emission of nitrogen oxides into the atmosphere from any existing process producing products of organic nitrations and/or oxidations using nitric acid to exceed 5.0 kg of nitrogen oxides (expressed as nitrogen dioxide) per metric tonne of nitric acid (100 percent acid basis) used in such process (10.0 lbs/T).
c) Exemption. Subsections (a) and (b) of this rule shall not apply to any industrial process using less than 90.7 metric tonnes (100 tons) of nitric acid (100 percent acid basis) annually or which produces less than 907 kg (1 ton) of nitrogen oxides (expressed as nitrogen dioxide) per year.