This decision addresses petitions for review that challenge an Outer Continental Shelf (“OCS”) Permit to Construct and Title V Air Quality Operating Permit (“Permit”) Region 10 (“Region”) of the U.S. Environmental Protection Agency (“EPA” or “Agency”) issued to Shell Offshore, Inc. (“Shell”). The Region issued the Permit on October 21, 2011, pursuant to Clean Air Act (“CAA or “Act”) section 328, 42 U.S.C. § 7627, and applicable regulations governing air emissions from OCS sources at 40 C.F.R. part 55, and pursuant to Title V of the CAA, 42 U.S.C.