35 Ill. Adm. Code 204.500
Major Source Baseline Date
Section 204.500 Major Source Baseline Date
"Major source baseline date" means:
a) In the case of PM
10
and SO
2
, January 6, 1975;
b) In the case of NO
2
,
February 8, 1988; and
c) In the case of PM
2.5
,
October 20, 2010.