As part of an effort to assess the potential impacts associated with global climate change, the U.S. Environmental Protection Agency's Office of Research and Development is supporting global atmospheric chemistry research by developing global scale estimates of volatile organic compound (VOC) emissions (excluding methane). Atmospheric chemistry models require, as one input, an emissions inventory of VOCs. Consequently, a global inventory of anthropogenic VOC emissions has been developed. The inventory includes VOC estimates for seven classes of VOCs: paraffins, olefins, aromatics (benzene, toluene, xylene), formaldehyde, other aldehydes, other aromatics, and marginally reactive compounds. These classes represent general classes of VOC compounds which possess different chemical reactivities in the atmosphere. The technical approach used to develop this inventory involved four major steps. The first step was to identify the major anthropogenic sources of VOC emissions in the United States and to group these sources into 28 general source groups. Source groups were developed to represent general categories such as “sources associated with oil and natural gas production” and more specific categories such as savanna buming. Emission factors for these source groups were then developed using different techniques and data bases. For example, emission factors for oil and natural gas production were estimated by dividing the United States' emissions from oil and gas production operations by the amount of oil and natural gas produced in the United States. Multiplication of these emission factors by production/consumption statistics for other countries yielded global VOC emission estimates for specific source groups within those countries. The final step in development of the VOC inventory was to distribute emissions into 10° by 10° grid cells using detailed maps of population and industrial activity. The results of this study show total global anthropogenic VOC emissions of about 110,000 Gg/yr. This estimate is about 10% lower than global VOC inventories developed by other researchers. The study identifies the United States as the largest emitter (21% of the total global VOC), followed by the (former) USSR, China, India, and Japan. Globally, fuel wood combustion and savanna burning were among the largest VOC emission sources, accounting for over 35% of the total global VOC emissions. The production and use of gasoline, refuse disposal activities, and organic chemical and rubber manufacturing were also found to be significant sources of VOC emissions.

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Past efforts to estimate methane emissions from underground mines, surface mines, and other coal mine operations have been hampered, to different degrees, by a lack of direct emissions data. Direct measurements have been completely unavailable for several important coal mining operations. A primary goal of this study was to collect new methane emissions measurements and other data for the most poorly characterized mining operations and use these data to develop an improved methane emission inventory for the U.S. coal mining industry. This required the development and verification of measurement methods for surface mines, coal handling operations, and abandoned underground mines and the use of these methods at about 30 mining sites across the United States. Although the study's focus was on surface mines, abandoned underground mines, and coal handling operations, evaluations were also conducted to improve our understanding of underground mine emission trends and to develop improved national data sets of coal properties. Total U.S. IMPLICATIONSEstimates vary somewhat, but methane emissions from coal mines comprise ~15% of total domestic anthropogenic methane emissions. This study substantially increases the reliability of these estimates by adding emission measurements from 30 separate coal mine sites. Sampling efforts have focused on underrepresented mining categories including surface mines, abandoned mines, and handling facilities. Two new quality-assured and verified measurement methods have been developed for surface mines and coal handling facilities. The single path and plane-integrated open-path Fourier transform infrared (FTIR) spectroscopy techniques developed for surface mines have since been adopted for a number of other applications including landfills and animal containment facilities.

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This paper describes a methodology developed for the purpose of estimating emissions factors of organic compounds from a variety of different area sources in a rapid and cost effective manner. The methodology involves the use of an open-path fourier transform infrared (FTIR) spectrometer to measure concentrations of hydrocarbon and other compounds in plumes emanating from area sources. Meteorological measurements are also collected and used in conjunction with an appropriate plume dispersion model to relate measured plume and background concentrations to an emission rate for the source. This study was conducted to validate the performance of the measurements methodology, and to support the development of measurements methodology protocols, field setup guidelines, data analysis procedures, and other information needed to conduct more effective and accurate measurements. Based on the results, it appears that the methodology is capable of estimating the emissions from an area source with an accuracy of at least ± 25 to 30 percent. Recent studies have been conducted to assess the ability of open-path FTIR systems to collect representative ambient measurements. 56 These studies suggest that, over a wide range of compounds, concentration measurements from FTIR systems compare well with concentrations collected using accepted techniques. Recently, the emission rate estimation method described was field tested by the U.S. Environmental Protection Agency (EPA) in support of determining methane (CH 4) emission rates from surface coal mines. 4 This test revealed that the methodology