hydrogen sulphide

Flammable, poisonous gas with characteristic odour of rotten eggs, perceptible in air in a dilution of 0.002 mg/l. It is used as a reagent in chemical analysis; extremely hazardous; collapse, coma and death from respiratory failure may come within a few seconds after one or two inspirations; low concentrations produce irritation of conjunctiva and mucous membranes. Headache, dizziness, nausea, lassitude may appear after exposure. (Source: MGH / INDMER)