As of 1 January 2008, Berlin has an Environmental Zone (Umweltzone) bounded by the outer S-Bahn ring that is designed to regulate car emissions in the city centre. The aim is to reduce the fine particulate matter Feinstaub, which are worsening Berlin’s air quality. To drive within the zone, a driver needs a sticker certifying that his or her car meets the city’s emission standards. More information can be found at www.berlin.de/umweltzone.