Ill. Admin. Code tit. 35 § 270.408
A request to continue to operate an emission unit in excess of the standards or limitations of Subchapter c of Chapter I of the Board's Air Pollution regulations (35 Ill. Adm. Code 212 et seq.) during a malfunction or breakdown of the emission unit or related air pollution control equipment, if desired, must be contained in the CAAPP application and shall include, at a minimum, a detailed explanation of why such continued operation will be necessary; the nature of any anticipated malfunction or breakdown; emission points and quantities of emissions which will occur during such continued operation; the anticipated length of time during which such operation will continue; all measures, such as use of off-shift labor or equipment, which will be taken to minimize the quantity of air contaminant emissions and length of time during which such operation will continue; and the calculations used to determine the above information. The Agency may grant permission to operate during a malfunction or breakdown in accordance with 35 Ill. Adm. Code 201.262.
Ill. Admin. Code tit. 35, § 270.408