Update on Implementation of New Source Review Requirements for PM2.5

The Air Quality Bureau is no longer taking comment on draft modeling guidance documents that included provisions for the modeling of particulate matter is with a diameter less than or equal to 2.5 microns (PM2.5). Permitting and modeling requirements for PM2.5 will not be implemented until all federal rules for the implementation of the New Source Review program for PM2.5 have been promulgated by EPA and adopted into state administrative code.

Particulate matter with a diameter less than or equal to 10 microns (PM-10) will continue to be used as a surrogate for PM2.5 for permitting and modeling purposes during this period. For areas with design values for PM2.5 that exceed the PM2.5 National Ambient Air Quality Standards, additional analyses for PM2.5 may be required.

EPA recently promulgated rules that specify what emissions levels trigger New Source Review requirements for PM2.5. However, EPA has not finalized proposed rules for PM2.5 increments, significant impact levels, and significant monitoring concentrations. Questions regarding EPA’s New Source Review rules for PM2.5 and their implementation may be directed to Jim McGraw at jim.mcgraw@dnr.iowa.gov or at (515) 242-5167.