The EPA is proposing to change the definition of “Regulated NSR pollutant” with regard to particulate matter.

Amendment to the Definition “Regulated NSR Pollutant” Concerning Condensable Particulate Matter

Implementation of the New Source Review (NSR) Program for Particulate Matter Less Than 2.5 Micrometers (PM2.5): Amendment to the Definition “Regulated NSR Pollutant” Concerning Condensable Particulate Matter

The EPA is proposing to revise the definition “regulated NSR pollutant” contained in two sets of Prevention of Significant Deterioration (PSD) regulations and in the EPA's Emission Offset Interpretative Ruling. This revision would correct an inadvertent error made in 2008 when the EPA issued its final rule to implement the new source review (NSR) program for fine particles with an aerodynamic diameter of less than or equal to 2.5 micrometers (PM2.5). Effectively, this revision would reestablish the interpretation that for measurement of “particulate matter emissions” in the context of the PSD and NSR regulations, there is no explicit requirement to include measurement of condensable PM. However, the condensable portion would continue to be required for emissions of particles with an aerodynamic diameter of less than or equal to 10 micrometers (PM10 and PM2.5).

Why is EPA proposing to change the definition “Regulated NSR pollutant” with regard to PM?

When EPA proposed to amend the PSD rules to address new requirements for PM2.5 in 2005, they proposed to revise the definition “regulated NSR pollutant” to add PM2.5 as a regulated criteria pollutant and to require that, for purposes of determining PSD applicability and setting emissions limitations for a particular proposed source or modification, emissions of PM10 and PM2.5 included the condensable portion of particulate matter that could be emitted by the source or modification.

Specifically, the proposed regulatory text provided that “Particulate matter (PM10 and PM2.5) emissions include gaseous emissions from a source or activity which condense to form particulate matter at ambient temperatures.” In that text, EPA had not intended to include the PM indicator referred to as “particulate matter emissions”; instead, EPA intended the proposed text as a “shorthand” terminology encompassing both “PM10 emissions” and “PM2.5 emissions.”

Moreover, EPA did not receive any comments suggesting that the “PM emissions” indicator should be included in the provision requiring the inclusion of condensable PM. Nevertheless, in the final stages of preparing the 2008 final rule, the proposed text “Particulate matter (PM10 and PM2.5) emissions,” was revised to read “Particulate matter (PM) emissions, PM10 emissions and PM2.5 emissions.” Thus, the inadvertent editorial change made in the final rule added “Particulate matter (PM) emissions” as a third indicator for PM to the sentence for which the PSD regulations would require that condensable PM be included.

EPA also notes that the 2008 final rule added the term “particulate matter (PM) emissions” to the definition “regulated NSR pollutant” at 40 CFR part 51 Appendix S (the EPA’s “Emission Offset Interpretative Ruling”). This was clearly a mistake because that rule pertains to new source review in nonattainment areas (and to sources locating outside nonattainment areas that impact air quality in a nonattainment area). That being the case, Appendix S is not intended to address non-criteria pollutants, since nonattainment areas apply only to criteria pollutants.

Comments must be received on or before May 15, 2012. If anyone contacts the EPA requesting the opportunity to speak at a public hearing concerning the proposed regulation by March 26, 2012, the EPA will hold a public hearing approximately 30 days after publication in the Federal Register. Additional information about the hearing would be published in a subsequent Federal Register notice.

More information regarding this topic can be found in Federal Register Volume 77, Number 52.