Prevention of Significant Deterioration (PSD) for Particulate Matter Less Than 2.5 Micrometers (PM2.5)-Increments, Significant Impact Levels (SILs) and Significant Monitoring Concentration (SMC)

The EPA is amending the requirements for particulate matter less than 2.5 micrometers (PM<INF>2.5</INF>) under the Prevention of Significant Deterioration (PSD) program by adding maximum allowable increases in ambient pollutant concentrations ("increments") and two screening tools, known as the Significant Impact Levels (SILs) and a Significant Monitoring Concentration (SMC) for PM<INF>2.5</INF>. The SILs for PM<INF>2.5</INF> are also being added to two other New Source Review (NSR) rules that regulate the construction and modification of any major stationary source locating in an attainment or unclassifiable area, where the source's emissions may cause or contribute to a violation of the national ambient air quality standards (NAAQS).