The goal of this work is to develop a comprehensive, high-quality database characterizing PM2.5 emissions from utility plants firing high sulfur coals. The specific objectives are to: 1) develop and test an ultra low-NOx pulverized coal burner for plug-in retrofit applications without boiler wall tube modifications, 2) assess the impact of low-NOx PC burner operation on NOx and PM2.5 emissions, and 3) provide high-quality data to ensure that future PM2.5 regulations are based on good scientific information. The work will be performed in the Clean Environment Development Facility (CEDF), a 100 million Btu/hr near-full-scale facility located at the Alliance Research Center.