http://en.wikipedia.org/wiki/Hydrogen_sulfide
• 0.0047 ppm is the recognition threshold, the concentration at which 50% of humans can detect the characteristic odor of hydrogen sulfide [1],
normally described as resembling "a rotten egg".
• 10-20 ppm is the borderline concentration for eye irritation.
• 50-100 ppm leads to eye damage.
• At 150-250 ppm the olfactory nerve is paralyzed after a few inhalations, and the sense of smell disappears, often together with awareness of
danger,
• 320-530 ppm leads to pulmonary edema with the possibility of death.
• 530-1000 ppm causes strong stimulation of the central nervous system and rapid breathing, leading to loss of breathing;
o 800 ppm is the lethal concentration for 50% of humans for 5 minutes exposure(LC50).
• Concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath.
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