Definition

H2S is a colorless, flammable, poisonous, and corrosive gas with one sulfur atom bonded to two hydrogen atoms. It is also known as sewer gas, swamp gas, or manure gas. H2S has a noticeable rotten-egg odour detectable at concentrations as low as 0.5 ppb. It is a highly flammable, explosive gas between 4% and 45% (concentration in air) which may travel to ignition sources and flash back. When ignited, it burns to produce toxic vapors and gases (sulfur oxides).