A global inventory of volatile organic compound emissions from anthropogenic sources

Abstract

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.