Hydrogen sulfide (H₂S) is a colourless gas known for its characteristic “rotten egg” smell. It is produced naturally by the decomposition of organic matter and is also released from industrial activities such as wastewater treatment and oil and gas processing.
At low concentrations, H₂S can cause irritation of the eyes and respiratory system. At higher levels, it can pose more serious health risks. Monitoring H₂S is important for identifying local pollution sources and managing odour-related concerns.