Baseline Year for the Baseline Year Test (in 40 CFR 93.119)

Certain nonattainment areas are required to use one or both of the interim emissions tests before they have adequate or approved motor vehicle emissions budgets for the relevant national ambient air quality standard (NAAQS). Please consult 40 CFR 93.109 to determine the test(s) applicable to your area.

One of the interim emissions tests is the baseline year test, where projected on-road mobile source emissions are compared to on-road mobile source emissions in the baseline year. The following table indicates what baseline year must be used for comparison for each relevant NAAQS. Please refer to 40 CFR 93.119 for additional details about the baseline year test.

For additional information about NAAQS, please refer to EPA’s NAAQS website.

For information about areas designated nonattainment for each NAAQS, refer to EPA’s Green Book website.