| Abstract |
Over the last fifteen years, the regulatory requirements for particulate matter (PM) species (namely, PM10 and PM2.5) have become increasingly more rigorous, and our technical understanding of PM emissions sampling has grown significantly. Even so, environmental professionals continue to rely on the historic and conservatively high EPA AP-42 emission factors for estimating PM emissions from fossil fuel-fired combustion units. Demonstrating compliance with the more restrictive PM2.5 NAAQS requires more representative PM species emission estimates to assure that PM2.5 emissions are not unrealistically over-estimated, especially for gas-fired combustion units typically found at refineries and chemical plants. Data collected in test method research programs co-sponsored by governmental and non-governmental organizations within the last 10 years provide more accurate information about PM2.5 emissions formed by gas (natural gas and refinery gas) and oil combustion, and how to more accurately measure PM2.5 emissions in the stack. However, despite this information, AP-42 emission factors for turbines, boilers, and heaters remain unchanged. Even so, technical environmental professionals (within both the private sector and government) are beginning to rely on the available supporting technical information from these research studies to estimate emissions for combustion units, using alternate PM emission factors that better represent actual PM2.5 emissions. This paper summarizes the PM2.5 emission measurement research results for gas-fired combustion units, presents recent successful uses of such alternate PM emission factors by the regulated community and identifies next steps needed to improve PM10 and PM2.5 emission factors. |
