For the thorough understanding of the atmospheric fate and transport of Hg it is necessary to document and comprehend the distribution and extent of emissions from point sources and from more diffuse sources, whether these are of anthropogenic origin or due to natural sources and processes. This report provides an evaluation and summation of the current state of the science and of the extent of current efforts to document and understand the degree to which concentrations in the atmosphere are changing, and whether this is entirely due to changes in inputs of Hg into the biosphere, or due to changes in other pollutants or chemicals, or global climate. Both direct and indirect impacts of Hg fate and transport through the atmosphere need to be considered.
