(a) An increase in emissions from operational or physical changes at a facility, or emissions unit at a major stationary source, covered by a plant-wide applicability limit (PAL) permit is insignificant, for the purposes of major new source review under this subchapter, if the increase does not exceed the PAL.(b) At no time are emissions reductions of a PAL pollutant that occur during the PAL effective period creditable as decreases for purposes of offsets, unless the level of the PAL is reduced by the amount of such emissions reductions and such reductions would be creditable in the absence of the PAL.(c) A physical or operational change not causing an exceedance of a PAL is not subject to federal restrictions on relaxing enforceable emission limitations to avoid new source review.