The National Association of Clean Air Agencies (“NACAA”) has submitted October 27th comments to the United States Environmental Protection Agency on its proposed revisions to the Guideline on Air Quality Models (40 C.F.R. Part 51, Appendix W) (“Guideline”).
The proposed revisions were published in the Federal Register on July 29, 2015. See 80 Fed. Reg. 45,340.
The NACAA describes itself as a non-partisan, non-profit association of air pollution control agencies in 40 states, the District of Columbia, four territories and 116 metropolitan areas.
An important aspect of the Clean Air Act is its focus on ambient air quality standards. Various methods and techniques are used to determine the quantity of a given pollutant in the ambient air. A key technique is air quality dispersion modeling.
Air quality modeling is often utilized to estimate the probable concentration of a given pollutant at a certain geographic point. Therefore, the models are an important tool in the effort to determine what impact a given quantity of pollutants will have on ambient provisions such as the National Ambient Air Quality Standards.
The Guideline provides EPA-recommended models and other techniques, as well as guidance for their use.
The NACAA expresses support of the proposed revisions to the Guideline noting in part:
In general, NACAA is supportive of the proposed changes and believes they have been adequately vetted by the modeling community. Thus, we believe EPA is on sound footing to recommend these updates to the regulatory default version of AERMOD. We encourage EPA to continue working with state and local air agencies to evaluate the modeling system on an ongoing basis and to develop improvements for future versions of the model and updates to the Guideline. NACAA also supports EPA’s proposal to replace the CALINE3 family of models with AERMOD as the preferred model for mobile source modeling for carbon monoxide (CO), particulate matter (PM) and lead. This change is both practical and sensible, as CALINE3 requires meteorological input data that are no longer supported, and for the other reasons set forth in the proposal’s preamble.
The organization does focus comments on what it characterizes as “several key elements that concern us” which include:
- Proposed approach for addressing single-source impacts on ozone and secondary PM2.5
- Status of CALPUFF
- Prognostic meteorological data
- Status of EPA model clearinghouse
Click here to download a copy of the comments.
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