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PM2.5 and PM10 Hot-Spot Analyses in Project-Level Transportation Conformity Determinationas for the New PM2.5 and Existing PM10 National Ambient Air Quality Standards

Final Rule Summary - March 10, 2006


This rule finalizes provisions regarding PM2.5 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 PM2.5 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

Categorical Hot-Spot Findings

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).

Updated: 7/3/2013
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