40 CFR § 60.31e - Definitions.

Terms used but not defined in this subpart have the meaning given them in the Clean Air Act and in subparts A, B, and Ec of this part.

Standard Metropolitan Statistical Area or SMSA means any areas listed in OMB Bulletin No. 93–17 entitled “Revised Statistical Definitions for Metropolitan Areas” dated June 30, 1993 (incorporated by reference, see § 60.17).