The invisible threat: A case report on sewer gas poisoning

Hydrogen sulphide (H₂S) is a toxic gas produced during the decomposition of organic matter and is frequently encountered in sewers and sewage treatment facilities. Fatal exposure to hydrogen sulphide is generally accidental and is particularly associated with occupational exposure and poorly ventilated or confined spaces. At relatively low concentrations, H₂S can be recognised by its characteristic rotten-egg odour. However, this odour is an unreliable warning at higher concentrations.This case report describes an acute and fatal exposure to H₂S in a confined sewer environment, highlighting the rapid onset of toxicity and the forensic findings observed. The incident resulted in sudden collapse and death, with post-mortem examination revealing greyish-green discolouration of blood and tissues, pulmonary oedema, and petechial haemorrhages, consistent with severe H₂S intoxication. Secondary exposure during attempted rescue also occurred, underscoring the risk to unprotected rescuers. Occupational settings with poor ventilation and decomposing organic matter remain high-risk for H₂S poisoning, and prompt atmospheric assessment and protective measures are crucial to prevent further casualties.Hydrogen sulphide, Fermentation, Organic Matter, Sewage, Paralysis.