The Environmental Zone
Only low-emission vehicles are allowed into Berlin's environmental zone in order to reduce air pollution caused by diesel soot (particulate matter) and nitrogen oxides. These vehicles must be identified by a green sticker. Vehicles with high pollutant emissions are not permitted to drive or park within the low emission zone.
The environmental zone covers the centre of Berlin inside the S-Bahn ring ("Großer Hundekopf"). A green sticker is required in order to drive within the environmental zone.