In response to worsening air pollution problems in many of Europe’s largest cities, Barcelona (Spain) and Munich (Germany) have been moved to action. In Barcelona’s case, voluntarily, and in Munich’s case, as the result of a court order. To be more specific, Barcelona will begin banning cars older than 20 years in 2019, and Munich was ordered by Bavaria’s highest administrative court that the state and city to develop “clean air” plans that will include diesel car bans (when necessary) by the end of 2017.