b) For Federal actions not covered by subsection (a) of this Section and not exempt pursuant to Section 255.170 of this Part, a conformity determination is required for each pollutant where the total of direct and indirect emissions in a nonattainment or maintenance area caused by a Federal action would equal or exceed any of the rates in subsection (b)(1) or (b)(2) of this Section:

1. 1) Nonattainment Areas:

   	Tons/Year
   Ozone (VOC's or NOx):
   Serious NAA's	50
   Severe NAA's	25
   Extreme NAA's	10
   Other ozone NAA's outside an ozone transport region	100
   Marginal and moderate NAA's inside an ozone transport region:
   VOC	50
   NOx	100
   Carbon monoxide:
   All NAA's	100
   SO2 or NO2:
   All NAA's	100
   PM-10:
   Moderate NAA's	100
   Serious NAA's	70
   Pb:
   All NAA's	25

2. 2) Maintenance Areas:

   	Tons/Year
   Ozone (NOx) SO2 or NO2:
   All maintenance areas	100
   Ozone (VOC's):
   Maintenance areas inside an ozone transport region	50
   Maintenance areas outside an ozone transport region	100
   Carbon monoxide:
   All maintenance areas	100
   PM-10:
   All maintenance areas	100
   Pb:
   All maintenance areas	25