METHODS FOR ATTRIBUTING AMBIENT AIR POLLUTANTS TO EMISSION SOURCES

▪ Abstract Six methods for attributing ambient pollutants to emission sources are reviewed: emissions analysis, trend analysis, tracer studies, trajectory analysis, receptor modeling, and dispersion modeling. The ranges of applicability, types of information provided, limitations, performance capabilities, and areas of active research of the different methods are compared. For primary, nonreactive pollutants whose effects of concern occur on a global scale, an accounting of emissions rates by source type and location largely characterizes source contributions. For other pollutants or smaller spatial scales, accurate estimates of emissions are needed for identifying the emissions reduction potentials of possible control measures and as inputs to dispersion models. Emission levels are frequently known with factor-of-two accuracy or worse, and improved estimates are needed for dispersion modeling. The analysis of regional or urban-scale trends in emissions and ambient pollutant concentrations can provide qua...