40 CFR §71.23

1. (a)Sources covered. The provisions of this subpart apply to an owner or operator of an existing source who is seeking a compliance extension under section 112(i)(5) of the Act and who, pursuant to part 63, subpart D, of this chapter, is required to file a permit application for the extension prior to the date a comprehensive title V permit program is approved for the State in which the existing source is located.
2. (b)Covered emissions. All hazardous air pollutant emissions from the early reductions source shall be included in permit applications and part 71 permits issued under this subpart.