Hemispheric Transport of Air Pollution 2010

Part A - Ozone and Particulate Matter

image of Hemispheric Transport of Air Pollution 2010
This is one part of a four-volume set that presents a state-of-the-science assessment of the intercontinental transport of air pollutants across the Northern Hemisphere. The first three volumes are technical assessments of the state-of-science with respect to intercontinental transport of ozone and particulate matter, mercury, and persistent organic pollutants. The fourth volume is a synthesis of the main findings and recommendations of Parts A, B, and C organized around a series of policy-relevant questions that were identified at the Task Force on Hemispheric Transport of Air Pollution’s first meeting.



Emission inventories and projections

Gridded global, regional, and national emission estimates exist for many of the pollutants that are important for assessing the hemispheric transport of air pollution (SO2, NOx, NMVOC, NH3, CH4, OC, BC, PM, and CO). Some of these are publicly available, whereas others are used by individual research groups or government agencies to study specific aspects of emissions or atmospheric processes. Most inventories are developed by combining emission factors, in units of mass of emissions per unit of activity, with activity levels or proxies thereof. The quality of emission inventories varies widely, however, and is difficult to assess objectively. For developed countries, the inventories for some pollutants from some sectors are viewed to be of high quality, as they have been crosschecked by field studies and laboratory tests and through air quality modelling. Examples of high-quality inventories would be the SO2 emissions from power generation in North America and Europe. For other pollutants and sectors, the quality of inventories may be considerably lower. For developing and newly industrializing countries, the quality of emission inventories is generally poor, due to a lack of actual emissions measurements and intensive ambient observations, incompleteness of the activity data, and absence of test-based emission factors. A shorter history of inventory development in these regions also means a lack of expertise and institutional capacity to perform such tasks. Many developing and newly industrializing countries lie within the Northern Hemisphere, and they provide challenges to the compilation of a complete and reliable inventory of all species.


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