To: Digestion List
Subject: Deadly H2S levels and corrosion
As we lost two men to H2S gas emitted ABOVE THE MANHOLE in 1984 I have become an expert on various aspects of H2S gas in a multitude of situations.
First of all H2S causes the olfactory nerve to become desensitized at very low concentrations. Therefore it is common that the potential victim gets a whiff of "rotten eggs" then believes that the odor went away. At this level there is danger of becoming overcome. H2S causes paralysis of the lung at high levels of concentration and brain death. Personnel involved in sewer maintenance are required to meter the content of the "confined space" prior to entry, but, in our case and similar ones, release of standing or septic sewage (that which remains stagnant for +-24 hours) or sudden aeration of standing sewage can produce a "cloud" of gas which is expelled from the confined space area into the atmosphere.
Unfortnuately, neither NIOSH nor OSHA concern themselves with detection outside of what is strictly described as a "confined space"... and do not warn of this potential. In our case, there had been a total of 9 other deaths in within the region in the previous 18 months!!!
Needless to say, I find it a worthwhile cause to speak whenever possible on this danger and to continue to write on the subject while attemping to find a responsive person within these agencies to include this risk in their training or employer regs.
Cordially, Mary Gayman
Pacific Sewer Maintenaance
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Updated 22 January 2004 by Paul Harris