Acid Rain stamp from 1986 in Sweden. Around this time I was active in a non-profit youth organization in Sweden and we inventoried the acid rain damage on spruces in our neighborhood as well as taped up protest posters against the acid rain falling over Sweden. A lot of the acid rain was created by German industries, but some was from within Sweden as well.  I remember well how we biked around taping posters at intersections without trying to get noticed by anybody (=police mostly) at 5 AM.  I don't think our parents knew, or if they did, they let us do it.  Nothing ever happened, no police car ever showed up... but the acid rain threat was real, and the forests were dying.  It is better now, because of better cleaning of exhausts from energy and other industrial plants. Oh, and of course the cars made a lot of acid rain.  Somehow it feels like we are fighting a bigger threat today, bigger and more omnipresent and more hard to grasp - global climate change. Back in the 80s, things were simpler, at least for us teenagers.