Dont believe everything on Wiki Nev (Wiki is not information validated by research and beholden to a particular author)- PS I have to agree with Pete on this one- the testament is the number of Emi discs from the 70s that were played on crappy record players but if you pick them up today they still play just as well. If they were affected by any aerosol acids or other chemicals natural or not in the air then they would probably disintegrate. The empircal evidence suggest they do not. I have 3 typical emidiscs from the 70s and they play just as good as they did in 1974 when I got them.