"ug" is an abbreviation for micrograms.
"M3" is an abbreviation for cubic meter.
"SO2" is an abbreviation for sulfur dioxide.
"TSP" is an abbreviation for particulate matter.
"NOx" is an abbreviation for nitrogen oxides.
"CO" is an abbreviation for carbon monoxide.
Ill. Admin. Code tit. 35, § 202.125