Can an MPO rely on a previous regional emissions analysis, or portion thereof, conducted for a 1-hour ozone conformity determination to determine conformity for the 8-hour ozone standard?
Yes, provided that they meet the requirements in 40 CFR 93.122(g). In particular, the regionally significant projects in the plan/TIP must be consistent with those assumed in the previous regional emissions analysis, and the design concept and scope of each regionally significant project cannot be significantly different from that assumed in the previous regional emissions analysis. In addition, the previous regional emissions analysis must be consistent with the requirements of 40 CFR 93.118 or 93.119, as appropriate. In particular, if the budget test is being performed under 93.118, the 8-hour attainment year must be included as an analysis year, and the previous regional emissions analysis must demonstrate conformity to all currently applicable budgets.
