"Prevention of Significant Deterioration Permit" or "PSD Permit" means a permit or the portion of a permit for a new major source or major modification that is issued by the Agency under the construction permit program required by Section 9.1(c) of the Act that has been approved by USEPA and incorporated into the Illinois SIP to implement the requirements of section 165 of the CAA and 40 CFR 51.166. [415 ILCS 5/3.363]
Ill. Admin. Code tit. 35, § 204.570