Uncertainties in the compilation of spatially resolved emission inventories - evidence from a comparative study

This paper examines the nature and extent of uncertainties associated with spatially resolved emission estimates with particular reference to an exami nation of alternative emissions data. Evidence is taken from recent researc h into the development of generic methodologies for the estimation of emiss ions of key urban pollutants from anthropogenic sources in the North West r egion of England. The inventory results, which are available in terms of a regional 5 x 5 km grid, a sub-regional 1 x 1 km grid and at the scale of th e original activity data, are useful for a number of air quality management tasks. However, the requirements of producing a generic methodology which uses readily available data sources has been found to limit the degree of d etail with which it is possible to develop estimation procedures and this h as implications for the level of confidence associated with the results and their further application. One of the principal limitations is the availab ility of equivalent activity data for a number of administrative units. A f urther assessment of the results of the North West inventory has been made through a comparative study of the inventory data with other emissions data covering a sub-set of the study area. These investigations indicate that t here are a number of variations between inventory results in terms of overa ll emission magnitudes and their spatial distribution. Observed differences between the estimates are attributable to different sources of activity da ta and emission factors and also as a result of the geographical data used to represent sources. (C) 1999 Elsevier Science Ltd. All rights reserved.