Array Insights

Regulated Particulate Matter: NSR/PSD vs. Title V

Total suspended particulates, TSP (referred to as particulate matter, PM, by EPA), is a regulated new source review (NSR) pollutant, so it is possible to go major source/prevention of significant deterioration (PSD) on this pollutant alone.  What’s tricky is that EPA replaced the TSP National Ambient Air Quality Standard (NAAQS) with the PM10 (particulate matter with an aerodynamic diameter of less than or equal to 10 micrometers) NAAQS, and this replacement was eventually recognized for Title V purposes, but not for NSR/PSD purposes.  The form of PM regulated under the NSR/PSD program is PM measured via Method 5, which collects large and small particles on a glass fiber filter at a temperature of approximately 250°F to prevent condensation.  EPA considers this form of PM more inclusive than TSP, which consists of particles collected by a high-volume ambient air sampler that are less than 30 microns, if condensable materials are ignored.