Ill. Admin. Code tit. 35 § 211.4130
Current through Register Vol. 48, No. 21, May 24, 2024
"Opacity" means that fraction of light, expressed in percent, which when transmitted from a source through a smoke-obscured path, is prevented from reaching the observer or instrument receiver.
Ill. Admin. Code tit. 35, § 211.4130
Amended at 20 Ill. Reg. 7590, effective May 22, 1996