Open Access

Table 1

H2S concentration for human contact time (Maddox, 1982).

Period of exposure Parts of H2S per million parts of air (ppm)
Maximum allowable concentration for prolonged exposure 10
Slight symptoms after exposure of several hours 70-150
Maximum concentration that can be inhaled for 1 h without serious consequences 170-300
Dangerous after exposure of 30 min to one hour 400-500
Fatal in exposure of 30 min or less 600-800

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