Air Emission Inventories in North America: A Critical Assessment

Abstract

Although emission inventories are the foundation of air quality management and have supported substantial improvements in North American air quality, they have a number of shortcomings that can potentially lead to ineffective air quality management strategies. Major reductions in the largest emissions sources have made accurate inventories of previously minor sources much more important to the understanding and improvement of local air quality. Changes in manufacturing processes, industry types, vehicle technologies, and metropolitan infrastructure are occurring at an increasingly rapid pace, emphasizing the importance of inventories that reflect current conditions. New technologies for measuring source emissions and ambient pollutant concentrations, both at the point of emissions and from remote platforms, are providing novel approaches to collecting data for inventory developers. Advances in information technologies are allowing data to be shared more quickly, more easily, and processed and compared in novel ways that can speed the development of emission inventories. Approaches to improving quantitative measures of inventory uncertainty allow air quality management decisions to take into account the uncertainties associated with emissions estimates, providing more accurate projections of how well alternative strategies may work. This paper discusses applications of these technologies and techniques to improve the accuracy, timeliness, and completeness of emission inventories across North America and outlines a series of eight recommendations aimed at inventory developers and air quality management decision-makers to improve emission inventories and enable them to support effective air quality management decisions for the foreseeable future. INTRODUCTIONAir quality management (AQM) in North America focuses on ensuring that concentrations of compounds in the ambient air are below the levels that are considered harmful to human health or the environment. Strategies developed to achieve these standards are based on reduction of emissions from specific source classes. The effectiveness of this approach depends on an accurate understanding of the relative contributions of the sources to ambient atmospheric pollution. An adequate knowledge of emissions sources and associated fluxes, both before and after emission controls are adopted, has long been recognized as a requirement for designing cost-effective air pollution control strategies. 1 Emission inventories are designed to systematically quantify the temporal and spatial distributions of the fluxes of primary pollutants and secondary pollutant precursors emitted by significant sources. This places emission inventories at the foundation of today's AQM strategies, and significant errors in inventories can, therefore, lead to the adoption of strategies that protect human health and the environment less effectively than possible. Emission inventory errors can be enormously expensive by requiring installation and operation of air pollution controls beyond the ...

Differences between measured and reported volatile organic compound emissions from oil sands facilities in Alberta, Canada

“…Also, we acknowledge the anonymous reviewers for their detailed comments, which helped improve the paper considerably. The CEMS data for SO 2 …”

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