The EPA is establishing a new Federal Reference Method (FRM) for measuring Lead (Pb) in total suspended particulate matter (TSP) collected from ambient air. This method is intended for use by analytical laboratories performing the analysis of Pb in TSP to support data collection for the Pb National Ambient Air Quality Standard (NAAQS). The existing FRM for Pb is designated as a new Federal Equivalent Method (FEM), and the currently designated FEMs are retained. This action avoids any disruption to existing Pb monitoring networks and data collection and does not affect the FRM for TSP sample collection (High-Volume Method).