Swedish pharmacy chain Apotek Hjärtat has teamed up with ad agency Åkestam Holst to create a billboard which features a man who, rather like that passive-aggressive friend who hates you smoking, starts to cough if you light up near him. The billboard contains a detector that recognises a cigarette being lit or the glow from it at a distance of 10-15 metres. Just one billboard was installed for the campaign, but the stunt has received wide coverage online so its message has reached many more people that way.

This isn’t the first time that Apotek Hjärtat and Åkestam Holst have had digital fun with billboards: the same brand and agency were also behind the digital poster installed in a subway station which saw a woman’s hair blow around as the train came in. Clever stuff.