The Ruhr has a single LEZ covering 820 km², covering the towns/cities of: Bochum, Bottrop, Castrop-Rauxel, Dortmund, Duisburg, Essen, Gelsenkirchen, Gladbeck, Herne, Herten, Mühlheim, Oberhausen, and Recklinghausen, see first map below.
There are also other LEZs in Nordrhein-Westfalen, in the cities of Aachen, Bonn, Dinslaken, Düsseldorf, Eschweiler, Hagen, Köln, Krefeld, Langenfeld, Mönchengladbach, Münster, Neuss, Remscheid, Siegen and Wuppertal. This can also be seen on the map of middle Germany via the homepage map or the Quickguide.
Ruhr LEZ from January 2012:
Key: Green area=LEZ, grey lines = exempted motorways, blue area=air quality management area.
Slightly more detailed maps are available for the West, East and North sections of the Ruhr area, where the individual town names can be more easily read. Please click on each of the links: West, East and North.
Website of the Ministry for the Environment and Nature Protection NRW.
Further information from UBA.