[(N1 x Release1) + (N2 x Release2) + (N3 x Release3) + (N4 x Release4)] / (Release1 + Release2 + Release3 + Release4) = Adjusted N
Where the "N" variables are the N values for each of the four substances as specified in this section and § 721.10188 , § 721.10189 , § 721.10190 and the "Release" variables are the number of kilograms released of the respective four substances (in units of kg/site/day) per § 721.91(a) .
40 C.F.R. §721.10187