Transportation Conformity Reference Guide
Section D: Specific Regional Emissions Analysis Requirements
Chapter 7 8-Hour Ozone Areas without Adequate or Approved 1-Hour Ozone SIP Budgets
Conformity Before Adequate or Approved 8-hour Ozone SIP Budgets
Which Pollutants are required for the Regional Emissions Analysis in Ozone Nonattainment Areas?
Conformity after 8-Hour Ozone SIP Budgets are Adequate or Approved
This chapter discusses the regional emissions analysis requirements specific to areas designated nonattainment under the 8-hour ozone standard that do not currently have an adequate or approved 1-hour ozone emission budget. Such areas were either not designated nonattainment or maintenance under the 1-hour ozone standard or they were not required to submit a control strategy SIP for the 1-hour ozone standard. Once the area has adequate or approved 8-hour ozone emission budgets, they must be used for all future conformity determinations in accordance with §93.118.
Conformity Before Adequate or Approved 8-hour Ozone SIP Budgets
40 CFR §93.109(d)
This paragraph applies to areas that were never designated nonattainment for the 1-hour ozone NAAQS and areas that were designated nonattainment for the 1-hour ozone NAAQS but that never submitted a control strategy SIP or maintenance plan with approved or adequate motor vehicle emissions budgets. This paragraph applies 1 year after the effective date of EPA's nonattainment designation for the 8-hour ozone NAAQS for an area, according to §93.102(d). In addition to the criteria listed in Table 1 in paragraph (b) of this section that are required to be satisfied at all times, in such 8-hour ozone nonattainment and maintenance areas conformity determinations must include a demonstration that the budget and/or interim emissions test requirements are satisfied as described in the following:
40 CFR §93.109(d)(2)-(4)
- In ozone nonattainment areas that are required to submit a control strategy implementation plan revision for the 8-hour ozone NAAQS (usually moderate and above and certain Clean Air Act, part D, subpart 1 areas), the interim emissions tests must be satisfied as required by §93.119 for conformity determinations made when there is no approved motor vehicle emissions budget from an applicable implementation plan for the 8-hour ozone NAAQS and no adequate motor vehicle emissions budget from a submitted control strategy implementation plan revision or maintenance plan for the 8-hour ozone NAAQS.
- Such an 8-hour ozone nonattainment area must satisfy the interim emissions test for NOx, as required by §93.119, if the implementation plan or plan submission that is applicable for the purposes of conformity determinations is a 15% plan or other control strategy SIP that addresses reasonable further progress that does not include a motor vehicle emissions budget for NOx. The implementation plan for 8-hour ozone NAAQS will be considered to establish a motor vehicle emissions budget for NOx if the implementation plan or plan submission contains an explicit NOx motor vehicle emissions budget that is intended to act as a ceiling on future NOx emissions, and the NOx motor vehicle emissions budget is a reduction from NOx emissions levels in 2002.
- Ozone nonattainment areas that have not submitted a maintenance plan and that are not required to submit a control strategy implementation plan revision for the 8-hour ozone NAAQS (usually marginal and certain Clean Air Act, part D, subpart 1 areas) must satisfy one of the following requirements:
- The interim emissions test required by §93.119; or
- The State shall submit to EPA an implementation plan revision for the 8-hour ozone NAAQS that contains motor vehicle emissions budget(s) and a reasonable further progress or attainment demonstration, and the budget test required by §93.118 must be satisfied using the adequate or approved motor vehicle emissions budget(s) (as described in paragraph (d)(1) of this section).
Before adequate or approved 8-hour ozone SIP budgets are established in 8-hour ozone areas that do not have 1-hour ozone SIPs, the regional emissions analysis is done using one or two interim emissions tests, depending on the area's classification or designation as described below. (69 FR 40019, July 1, 2004)
Marginal and Below Classifications and Subpart 1 Areas
These 8-hour ozone nonattainment areas include: 8-hour ozone areas classified marginal and 8-hour ozone areas designated nonattainment under Clean Air Act subpart 1. These areas must pass one of the following tests in accordance with §93.119 for conformity determinations that occur before adequate or approved 8-hour ozone SIP budgets are in place:
- Build-no-greater-than-no-build test; or
- No-greater-than-2002 emissions test.
Emissions in all analysis years from the transportation system, as modified by the proposed transportation plan/TIP ("build"), must be less than or equal to either the existing transportation system ("no build") in each of those analysis years or the transportation system in 2002 ("baseline") (69 FR 40019, July 1, 2004). Section D has more information on the interim emissions tests.
The same test must be used for each analysis year for a given conformity determination. In other words, an MPO may not use the build-no-greater-than-no-build test in one analysis year and the no-greater-than-2002 test in another analysis year within the same conformity determination. However, while no 8-hour ozone budgets are available, areas are free to choose which test for a conformity determination regardless of what test was used for a prior conformity determination. For example, if an MPO within a marginal 8-hour nonattainment area makes a conformity determination based on the build-no-greater-than-no-build test, this would not preclude them, prior to adequate or approved budgets, from making a future conformity determination based on the no-greater-than-2002 emissions test (69 FR 40020, July 1, 2004).
Moderate and Above Classifications
These areas include: 8-hour ozone nonattainment areas classified as moderate, serious, severe, and extreme. These areas must pass both of the following tests in accordance with §93.119 for conformity determinations that occur before adequate or approved 8-hour ozone SIP budgets are in place:
- Build-less-than-no-build test; AND
- Less-than-2002 emissions test.
Emissions in all analysis years from the transportation system, as modified by the proposed transportation plan/TIP ("build"), must be less than the existing transportation system in each of those analysis years and the transportation system in 2002 (69 FR 40019, July 1, 2004). A "less than 2002" test is required in these areas instead of the "no-greater-than-2002 test" because the Clean Air Act specifically requires these areas to help reduce emissions. For more information regarding interim emissions tests, see Section D.
Which Pollutants are required for the Regional Emissions Analysis in Ozone Nonattainment Areas?
40 CFR §93.102(b)(2):
The provisions of this subpart also apply with respect to emissions of the following precursor pollutants:
(i) Volatile organic compounds (VOC) and nitrogen oxides (NOx) in ozone areas.
Regional emissions analyses must address both ozone precursors, which are nitrogen oxides (NOx) and volatile organic compounds (VOCs). Before budgets are available, areas must meet the appropriate interim emissions test(s) for both VOC and NOx precursors, unless EPA issues a NOx waiver for the 8-hour standard under Clean Air Act section 182(f). (69 FR 40020, July 1, 2004).
Conformity after 8-Hour Ozone SIP Budgets are Adequate or Approved
40 CFR §93.109(d)(1)
In such 8-hour ozone nonattainment and maintenance areas the budget test must be satisfied as required by §93.118 for conformity determinations made on or after:
- The effective date of EPA's finding that a motor vehicle emissions budget in a submitted control strategy implementation plan revision or maintenance plan for the 8-hour ozone NAAQS is adequate for transportation conformity purposes;
- The publication date of EPA's approval of such budget in the Federal Register; or
- The effective date of EPA's approval or such a budget in the Federal Register, if such approval is completed through direct final rulemaking.
Once a SIP for the 8-hour ozone standard is submitted with a budget(s) that EPA has found adequate or approved, the budget test must be used in accordance with §93.118 to complete all future applicable regional emissions analyses for 8-hour conformity determinations. The interim emissions test will no longer apply for that precursor.
For more information on the budget test please see Section D.
