Hydrogen sulphide is a poisonous gas with a chemical formula H₂S. It has no colour and an odour of rotten eggs. It is flammable in concentrations of between 4.3 to 46%. 

Hydrogen sulphide can be found naturally in crude oil and natural gas, or it can be produced by decomposing organic matter. Hydrogen sulphide gathers in sewers, volcanoes, well water and oil and gas wells. It can gather in low lying places and confined spaces because it is denser than air. Much of the hydrogen sulphide found in the atmosphere comes from food, waste and fossil fuel processing plants. 

Hydrogen sulphide is a temporary atmospheric pollutant commonly found in urban areas. It may form sulphur dioxide and sulphuric acid after being dissipated into the air. It is estimated to stay in the atmosphere for roughly 18 hours. Inhalation of high concentrations of hydrogen sulphide can be fatal to humans. 

Control of hyrdogen sulphide emissions can be acheived by optimising process conditions to favour lower production. Once produced hydrogen sulphide can be removed from gaseous streams by scrubbers or absorbtion towers. 

Alkali Environmental can perform periodic measurements of Hydrogen Sulphide in gaseous streams from stationary sources in line with the standard reference method US EPA method 11. We are currently working towards accreditation for this method whereby the reported results will carry UKAS and MCERTS accreditation where the method can be performed to the standard. 

These measurements are taken using a manual sampling train whereby a single result is obtained for a gas sample taken from the duct.