At the national level, average carbon monoxide (CO) concentrations have decreased substantially over the years
. As of September 2010, all CO nonattainment areas have been redesignated to maintenance areas. Federal requirements for modeling project-level “hot-spot” analyses with EPA MOVES (new model) and either CAL3QHC or AERMOD create challenges for state DOTs and other agencies responsible for project implementation. These challenges may be partly addressed through programmatic agreements
(PAs) and categorical findings
(CFs) for project-level analyses based on the new models and guidance. PAs need to meet National Environmental Policy Act (NEPA) requirements for transportation improvement projects in all locations. CFs need to meet federal transportation conformity rule requirement in designated nonattainment and maintenance areas. PAs are typically executed between state DOTs and the US DOT (FHWA/FTA). US DOT makes project level conformity determinations. The FHWA has recently initiated a process to develop, in consultation with EPA (in accordance with the requirements of the conformity rule), regional or multi-state CFs for both carbon monoxide (CO) and particulate matter (PM). This project is aimed at developing standard approaches to streamline air quality analyses relating to CO and PM.
(3) DOT, in consultation with EPA, may also choose to make a categorical hot-spot finding that (93.116(a) is met without further hot-spot analysis for any project described in paragraphs (a)(1) and (a)(2) of this section based on appropriate modeling. DOT, in consultation with EPA, may also consider the current air quality circumstances of a given CO nonattainment or maintenance area in categorical hot-spot findings for applicable FHWA or FTA projects.