PM_2.5 and PM₁₀ Hot-Spot Analyses in Project-Level Transportation Conformity Determinationas for the New PM_2.5 and Existing PM₁₀ National Ambient Air Quality Standards
Final Rule Summary

March 10, 2006

Background

This rule finalizes provisions regarding PM_2.5 and PM₁₀ hot-spot analyses as proposed in November 2003 and supplemented in December 2004 (See 68 FR 62690 and 69 FR 72140). A "hot-spot analysis" is an estimation of likely future localized PM_2.5 or PM₁₀ pollutant concentrations resulting from a new transportation project, and a comparison of those concentrations to the relevant National Ambient Air Quality Standards (NAAQS) (See 40 CFR 93.101). This rule establishes project-level criteria to demonstrate that statutory requirements of the Clean Air Act are met; i.e., that transportation activities do not create new violations, worsen existing violations, or delay timely attainment of the NAAQS. Hot-spot analyses must document that no new violations will be created and that the severity or number of existing violations will not increase as a result of the project.

General Requirements

• The hot-spot analysis must be completed for project-level conformity determinations for "projects of air quality concern" in PM₁₀ and PM_2.5 non-attainment and maintenance areas.
• However, PM₁₀ areas that have approved conformity SIPs that detail PM₁₀ hot-spot analysis criteria and procedures must continue to follow those criteria and procedures until the conformity SIP is updated.
• Quantitative hot-spot analysis will not be required until EPA releases quantitative modeling guidance and announces in the Federal Register that such requirements are in effect. EPA is currently developing a new motor vehicle emissions model, MOVES, which will be capable of estimating local emissions. EPA will consult with DOT and conformity partners when developing its future quantitative hot-spot modeling guidance.
• Until then, qualitative hot-spot analysis will be required.
• "Projects of air quality concern" are projects within a PM₁₀ and/or PM_2.5 nonattainment or maintenance area, funded or approved by FHWA or FTA, and are one of the following types of projects (See 40 CFR 93.123(b)(1)¹:
  • New or expanded highway projects that have a significant number of or significant increase in diesel vehicles;
  • Projects affecting intersections that are Level-of-Service (LOS) D, E, or F with a significant number of diesel vehicles, or those that will change to LOS D, E, or F, because of increased traffic volumes from a significant number of diesel vehicles related to the project;
  • New bus and rail terminals, and transfer points, that have a significant number of diesel vehicles congregating at a single location;
  • Expanded bus and rail terminals, and transfer points, that significantly increase the number of diesel vehicles congregating at a single location; and
  • Projects in, or affecting locations, areas, or categories of sites which are identified in the PM₁₀ or PM_2.5 applicable implementation plan or implementation plan submission, as appropriate, as sites of violation or possible violation.
• The remaining non-exempt projects that do not fall into the category of "project of air quality concern" do not require hot-spot analysis in order to meet the conformity requirements, because EPA has determine that these remaining projects would not have an adverse impact on air quality and meet the requirements of the CAA without further localized analysis.
• A qualitative PM_2.5 or PM₁₀ hot-spot analysis must consider both applicable air quality standards (annual and 24-hour), unless it is determined that meeting the controlling standard would ensure that Clean Air Act requirements are met for both standards.
• Other project-level conformity requirements continue to apply, including public involvement and interagency consultation.
• Re-entrained road dust must be considered in all PM₁₀ hot-spot analyses.
• Re-entrained road dust must be considered in a PM_2.5 hot-spot analysis ONLY IF road dust has been found by EPA or the State air agency to be a significant contributor to the PM_2.5 air quality problem in a given area.

Categorical Hot-Spot Findings

• FHWA and FTA, in consultation with EPA, can choose to make categorical hot-spot findings "as appropriate" in PM_2.5 and PM₁₀ nonattainment and maintenance areas for "projects of air quality concern." A project level conformity determination relying on categorical finding and meeting all other requirements is still required.
• Modeling used to support a categorical finding must be based on appropriate motor vehicle emissions factor model, dispersion model, and EPA's future quantitative hot-spot modeling guidance.
• As a result, categorical hot-spot findings will not be made prior to EPA's announcement in the Federal Register that quantitative PM_2.5 and PM₁₀ hot-spot analyses are required.

¹An example of a project of air quality concern would be a project on a new highway that serves a significant volume of diesel truck traffic, such as facilities with greater than 125,000 annual average daily traffic (AADT) and 8% or more of such AADT is diesel truck traffic. Further examples are provided within the preamble to the rule (See71 FR 12491).