Determination of Traffic Emissions from Pollution Measurements and DispersionModelling A contribution to subproject SATURN Ole Hertel\ Ruwim Berkowicz*, Finn Palmgren\ Eugene Genikhovich^, Alexander Ziv^ and Ekaterina lakovleva^ ^National Environmental Research Institute, Frederiksborgvej 399, DK-4000 Roskilde, Denmark ^Main Geophysical Observatory, Kurbysheva, St. Petersburg, Russia Introduction In most European cities emissions from road traffic has become the most important source of local air pollution. Monitoring programmes are in operation in most larger European cities with the aim of following the development in local air quality and studying the impact of various pollution regulations. The later is not straightforward, since pollution levels do not only depend on the emissions but also on factors like street configuration and meteorological conditions. The relationship between emissions and pollution concentrations can be established by means of an air quality model describing the governing physical and chemical processes. The opposite procedure (an inverse method) can be formulated as: having air pollution measurements, emissions from traffic can be calculated applying the relationships described by an air quality model. Such a procedure was applied to measurements from an extensive monitoring site at Jagtvej, Copenhagen and using the Operational Street Pollution Model (OSPM) (Berkowicz et #/., 1997). In extensive tests on measurements from a number of monitoring sites, OSPM has shown to give a satisfactory description of the air pollutant dispersion in urban streets. The inverse method has previously been applied for estimation of benzene emission factors for the Danish car fleet (Palmgren et al, 1995) and will be implemented in a trafficair pollution surveillance project in St.Petersburg, Russia. Editors: P.M. Borrell and P. Borrell © 1999: WITPRESS, Southampton Transactions on Ecology and the Environment vol 28, © 1999 WIT Press, www.witpress.com, ISSN 1743-3541