API PUBL 4720:2002

Both the U.S. Environmental Protection Agency (EPA) and the American Petroleum Institute (API) have published toxic air pollutant emission factors for combustion sources. These emission factors are frequently used by industry to prepare emission inventories to satisfy regulatory reporting requirements. State and federal agencies also use them to identify emission reduction priorities. While there is some agreement between the two data sets, there are many inconsistencies between the two. In addition, many of the factors are based on very limited data sets or are missing altogether. This study compares and explains differences in published toxic air pollutant emission factors for combustion sources and recommends priorities for gathering additional emission factor information. The specific objectives of this project were: -- To compare the emission factors published by EPA and API to identify gaps and inconsistencies. -- To identify available emission test data that can potentially be used to verify published factors and fill in existing gaps. -- To recommend additional field-testing or other efforts needed to fill in gaps or resolve inconsistencies. This report describes the efforts completed to meet these objectives.