Gas Fired Heater — Test Report Site B: Characterization of Fine Particulate Emission Factors and Speciation Profiles from Stationary Petroleum Industry Combustion Sources In 1997, the U.S. Environmental Prot ection Agency (EPA) promulgated new ambient air standards for partic ulate matter (PM) smaller than 2.5 micrometers in diameter (PM 2.5). Source emissions data are needed to assess the contribution of petrol eum industry combustion sources to ambient PM 2.5 concentrations. This report presents particulate measurement results from a 114 mill ion British thermal unit (MMBtu) per hour gas - fired refinery process heater. The particulate stack measurements were made using both a dilution tunnel research test method and traditional EPA sampling methods