What is Hydrogen Sulphide?
Hydrogen sulphide is a chemical compound with the molecular formula H2S. It’s commonly produced by bacteria in the absence of oxygen, which typically occurs in sewers and swamps.
Hydrogen sulphide is also a by-product of many industrial processes and tends to accumulate in low areas with poor ventilation since it’s heavier than air. It’s colourless and has the characteristic odour of rotten eggs, although it quickly deadens the sense of smell. Hydrogen sulphide is also highly toxic and flammable, making it a significant industrial hazard. It should also be noted that high concentrations of hydrogen sulphide are considered lethal.
How Are Workers Exposed to Hydrogen Sulphide?
Inhalation is the primary route of exposure for hydrogen sulphide in the workplace, although it can also be absorbed through the skin as a liquid.
Agricultural workers have a low risk of exposure to hydrogen sulphide since it’s produced by manure.
Oil and Gas Sector
Oil and Gas workers have a high risk of exposure as Hydrogen Sulphide or H2S can be found in hydrocarbon production and storage facilities. H2S occurs naturally in crude petroleum, natural gas, condensate, and produced water. H2S is produced by bacterial breakdown of organic materials and human/animal wastes (e.g., sewage).
Certain industry activities have the potential to release H2S, these include drilling and completions operations, flowback testing, plant operations, and well treatment and transportation of production fluids. H2S can also be produced as a by-product during the treatment of wells with mineral acids. The concentration of H2S may vary from field to field and during plant processes.
Pulp and Paper Production
Hydrogen sulphide may also be present in the production of paper and pulp as it is also a by-product of wood breaking down into pulp.
Workers working within the mining sector may be exposed if there are rocks present that contain hydrogen sulphide. There is potential for release of H2S during the milling of ore.
Additional sources of occupational exposure to hydrogen sulphide include the manufacture of rayon textiles as well as wastewater treatment.
What Are the Health Risks Associated with Exposure to Hydrogen Sulphide?
Health effects from chemical exposure vary depending on the products used. Hydrogen Sulphide is extremely toxic at very low concentrations and can kill in seconds by paralyzing the respiratory system.
Short-Term Health Risks
Hydrogen Sulphide is both an irritant (a material that causes redness and swelling) and a chemical asphyxiant (a material that interferes with the transportation or absorption of oxygen in the body). Worker fatalities are possible from exposures to high concentrations (>500 ppm) of H2S. Its health effects can vary depending on the concentration in air and length of exposure. Low concentrations irritate the eyes, nose, throat, and lungs (e.g. burning/tearing of eyes, cough and shortness of breath). People with asthma may experience breathing difficulties. The effects can be delayed for several hours, or sometimes several days, when working in low-level concentrations.
Long-Term Health Risks
Repeated or longer exposures may cause eye redness, headache, a feeling of tiredness, irritability, inability to sleep, upset stomach and weight loss. Moderate concentrations can cause more severe eye and lung irritation (including coughing, difficulty breathing, and pulmonary edema), headaches, dizziness, nausea, vomiting, staggering, and excitability.
The symptoms, which include pulmonary edema (buildup of fluid in the lungs), chest pains or shortness of breath, can be delayed for up to 72 hours after exposure. High concentrations can cause shock, seizures or spasms, inability to breathe, extremely rapid unconsciousness, comas, and death. Effects can occur within a few breaths, and possibly a single breath if concentrations are high enough.
Is Occupational Exposure to Hydrogen Sulphide at your workplace a concern?
If you work in areas were hydrogen sulphide is a concern regular air monitoring and testing by a qualified occupational health and safety professional should be done. Safe operating procedures for working with hydrogen sulphide need to be developed and implemented. An exposure control plan should be written for the worksite and implemented. Mandatory training of all employees in handling and emergency procedures should occur before any employee enter the worksite.
Trusted Hydrogen Sulphide Exposure Control Plans Approved by WorkSafeBC
The team at Chemscape Safety Technologies develops chemical management solutions designed to work with your business operations while meeting WorkSafeBC standards and industry regulations. Contact the team of occupational health and safety professionals to learn more about hydrogen sulphide exposure control plans for your business.