Greenpeace activists protest for clean air at "Denkpartner" statue in Stuttgart and demand action on the persistent air pollution in many German cities. The environmental activists fit the statue with a protective face mask. Greenpeace activists ask to act for a Blaue Plakette (blue badge) to get dirty diesel out of affected city districts. Banner reads: "Breathless through the city" .
Many cities suffer from a massive problem with nitrogen oxide. Nitrogen oxides are mainly caused by diesel motors.