I work with the stuff a fair bit as well. H2S is a dodgy one - when you can't smell it any more it's either a) dispersed and you're safe or b) at a concentration that means you're already going to die.
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Sat 13 Aug 2011, 14:58,
archived)
(Arsoles!)
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Sat 13 Aug 2011, 16:08,
archived)