Hydrogen Sulfide (H2S) Hydrogen sulfide is a colorless, flammable, extremely hazardous gas with a “rotten egg” smell. Some common names for the gas include sewer gas, stink damp, swamp gas and manure gas. It occurs naturally in crude petroleum, natural gas, and hot springs.
In addition, hydrogen sulfide is produced by bacterial breakdown of organic materials and human and animal wastes (e.g., sewage). Industrial activities that can produce the gas include petroleum/natural gas drilling and refining, wastewater treatment, coke ovens, tanneries, and kraft paper mills. Hydrogen sulfide can also exist as a liquid compressed gas.
High concentrations can cause shock, convulsions, inability to breathe, extremely rapid unconsciousness, coma and death. Effects can occur within a few breaths, and possibly a single breath. Protection against H2S exposure Before entering areas where hydrogen sulfide may be present:
- Air must be tested for the presence and concentration of hydrogen sulfide by a qualified person using air monitoring equipment, such as hydrogen sulfide detector tubes or a multi-gas meter that detects the gas. Testing should also determine if fire/ explosion precautions are necessary.
- If the gas is present, the space/area must be ventilated continually to remove the gas.
- If the gas cannot be removed, the person entering the space/area must use appropriate respiratory protection and any other necessary personal protective equipment, rescue and communication equipment.
Entering dangerous H2S atmospheres A level of H2S gas at or above 100 ppm is Immediately Dangerous to Life and Health (IDLH).
0-10 ppm Irritation of eyes, nose, and throat.
2 ppm Bronchial constriction in asthmatic individuals, spontaneous abortion
5-9.3 ppm Increased blood lactate concentration, decreased skeletal muscle citrate synthase activity
10-50 ppm Headache, dizziness, nausea, vomiting, coughing, difficulty breathing
150-250 ppm Olfactory paralysis
50-200 ppm Severe respiratory tract irritation, eye irritation/acute conjunctivitis, shock, convulsions, coma and death in severe cases