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, valid starting from 2005 there is an urgent call for action, particularly for fine dust (PM10). Current investigations (Junk & Helbig 2003, Reuter & building Mueller 2003) show that the limit values in certain places in congested areas are exceeded. Only if it is possible to located these Hot Spots purposeful measures to reduce the ambient air pollution can be conducted. For an efficient identification of these Hot Spots complex computer models or establishing special measurements networks are to expensive. Using the statistical model STREET 5,0 (KTT 2003) a cost-effective screening of the air pollution situation caused by the traffic can be done. STREET is based on the 3-dimensional micro-scale non-hydrostatic flowand dispersion model MISCAM (Eichhorn 1989). The results of over 100.000 different calculations with MISCAM are stored in a Database und these result are used to calculate the emissions with STREET. In collaboration with the city council more than 100 streets were investigated, mapped, and calculated. A special urban climate measuring network supplies the necessary meteorological input data about the wind filed and precipitation events in the valley of the Moselle. Information about road width and road orientation as well as building density were derived from aerial photographs. Traffic censuses and mobile air pollutants measurements with our instrument van supplied the remaining input data. We calculated the mean annual air pollutant concentrations for NO2, NO, CO, SO2, O3, benzene as well as PM10. A comparison of the model results with the values obtained from the stations of the central emission measuring network of Rhineland-Palatinate (ZIMEN annual report 2002) show very good agreements. The model was not only used to calculate the annual air pollutant but also for urban planning and management. The absolute level of the air pollutant is mainly dependent on the amount of traffic in the street canyons. Therefore different case-scenarios with varying quantity of traffic were calculated for each street. Furthermore the model can be used to find the maximum tolerable numbers of cars for a street without exceeding the air pollutant thresholds.