According to the European Environment Agency, Stockholm has the cleanest air of all European capitals, with Nordic capitals dominating the top rankings. Reykjavik and Helsinki follow in second and third places, respectively.
"Happiness isn't just about wealth or growth - it's about trust, connection and knowing people have your back," said Jon Clifton, the chief executive of Gallup. "If we want stronger communities and economies, we must invest in what truly matters: each other."