Besides being home to many of the world's foremost trade fairs, Hannover is also known for its environmental awareness. On 1 January 2008, Hannover joined Berlin and Cologne in an effort to lower the health risks associated with motor vehicle exhaust (especially diesel exhaust particulates) in their respective city centers. To accomplish this, Hannover has established an official "Emission Zone" roughly defined by the expressways (Schnellwege) encircling the city center. The Emission Zone is indicated by signs reading "Umwelt-Zone". Only vehicles which meet certain minimum requirements are permitted to enter the Emission Zone. To demonstrate compliance, an official permit (disc-shaped sticker) must be displayed on every vehicle's windshield.
Full details on the Hannover Emission Zone (PDF files):
