There has been much activity over the past six (6) months that will impact how air quality modeling analyses will be conducted for Prevention of Significant Deterioration (PSD) permit applications with respect to particulate matter less than 2.5 microns (PM2.5). As the resident air quality modeling expert at ALL4, I thought it was a good time to walk through each of these changes and discuss the potential challenges and yes, opportunities. Here is a list of what’s been happening over the last six (6) months:
- December 14, 2012 – U.S. EPA announced revised annual average PM2.5 National Ambient Air Quality Standards (NAAQS) reduced from 15 mg/m3 to 12 mg/m3,
- December 17, 2012 – U.S. EPA’s Office of Air Quality Planning and Standards (OAQPS) releases regulatory modeling update to AERMET and AERMOD (aka Version 12345),
- January 22, 2013 – DC Circuit Court vacated and remanded PM2.5 Significant Monitoring Concentrations (SMCs) and Significant Impact Levels (SILs),
- March 4, 2013 – U.S. EPA OAQPS issues draft PM2.5 modeling guidance for Regulatory Applications.
Each is briefly discussed below.