What about using nudges to reduce cigarette butts pollution?

Nowadays, cigarette butts are the most abundant form of plastic waste in the world, with about 4.5 trillion individual butts polluting our global environment. Solutions need to be found to reduce this negative environmental impact. Nudges could be a simple solution to reduce cigarette butts pollution. In this way, Social Proof and Dueling Preferences nudges were tested in a natural setting. Ashtrays using Social Proof or Dueling Preferences were experimented during 6 weeks in Bordeaux city, France. Comparatively, to control ashtray, Dueling Preferences ashtray was successful in reducing cigarette butts pollution. Social Proof ashtray was efficient too, but less efficient than Dueling Preference. Nudges using voting ashtrays (Dueling Preferences) seem to be a simple and realistic solution to decrease smoker's incivilities.