Estimation of Air Quality at Trier, Germany - a Case Study with STREET 5.

In the course of the European Council Directive on permissible air pollutant limit values, validstarting from 2005 there is an urgent call for action, particularly for fine dust (PM10). Current investigations(Junk and Helbig 2003, Reuter and building Mueller 2003) show that the limit values in certain places incongested areas are exceeded. Only if it is possible to located these Hot Spots purposeful measures to reducethe ambient air pollution can be conducted. For an efficient identification of these Hot Spots complexcomputer models or establishing special measurements networks are to expensive. Using the statistical modelSTREET 5,0 (KTT 2003) a cost-effective screening of the air pollution situation caused by the traffic can bedone. STREET is based on the 3-dimensional micro-scale non-hydrostatic flow- and dispersion modelMISCAM (Eichhorn 1989). The results of over 100.000 different calculations with MISCAM are stored in aDatabase und these result are used to calculate the emissions with STREET. In collaboration with the citycouncil more than 100 streets were investigated, mapped, and calculated. A special urban climate measuringnetwork supplies the necessary meteorological input data about the wind filed and precipitation events in thevalley of the Moselle. Information about road width and road orientation as well as building density werederived from aerial photographs. Traffic censuses and mobile air pollutants measurements with ourinstrument van supplied the remaining input data. We calculated the mean annual air pollutant concentrationsfor NO2, NO, CO, SO2, O3, benzene as well as PM10. A comparison of the model results with the valuesobtained from the stations of the central emission measuring network of Rhineland-Palatinate (ZIMENannual report 2002) show very good agreements. The model was not only used to calculate the annual airpollutant but also for urban planning and management. The absolute level of the air pollutant is mainlydependent on the amount of traffic in the street canyons. Therefore different case-scenarios with varyingquantity of traffic were calculated for each street. Furthermore the model can be used to find the maximumtolerable numbers of cars for a street without exceeding the air pollutant thresholds.