Air pollution monitoring in street canyons in North Rhine-Westphalia, Germany

Road traffic is one of the most important sources of air pollution in cities, According to a new section in the Federal Clean Air Act (Bundes-Immissionsschutzgesetz, BImSchG, Article 40, Section 2) authorities may restrict or even ban motor vehicle traffic under certain conditions in order to prevent or reduce harmful effects to the environment by traffic-caused air pollution. An ordinance proposed by the Federal Government will define the details. To prepare the implementation of the ordinance, the North Rhine-Westphalia State Environment Agency started a pilot programme to measure nitrogen dioxide, benzene, soot and other air pollutants at two sites with heavy traffic in Düsseldorf and Essen. The essentials of the proposed ordinance, the monitoring programme and results of the measurements are presented. It has been found that the standards which are to go into effect initially according to the proposed ordinance have not been exceeded.