EPA is taking final action to approve a revision to the State Implementation Plan (SIP), submitted by the State of North Carolina, through the North Carolina Department of Environment and Natural Resources' (NC DENR) Division of Air Quality, to EPA on August 11, 2010, for parallel processing. NC DENR submitted the final version of this SIP revision on May 17, 2011. The SIP revision establishes new NC DENR air quality regulations, specific to the regulation of greenhouse gases (GHGs) under North Carolina's New Source Review (NSR) Prevention of Significant Deterioration (PSD) program. Specifically, the SIP revision establishes appropriate emission thresholds for determining which new stationary sources and modification projects become subject to North Carolina's PSD permitting requirements for their GHG emissions. This rule incorporates state law changes into the federally approved SIP, and specifically, clarifies the applicable thresholds in the North Carolina SIP for GHG PSD requirements. EPA is approving North Carolina's May 17, 2011, SIP revision because the Agency has made the determination that this SIP revision is in accordance with the Clean Air Act (CAA or Act) and EPA regulations, including regulations pertaining to PSD permitting for GHGs. Additionally, EPA is responding to adverse comments received on EPA's November 5, 2010, proposed approval of North Carolina's August 11, 2010, draft SIP revision.