Hydrogen sulfide caused 60 worker deaths between 2001 and 2010.
Hydrogen sulfide is a chemical compound with the formula H2S. It is an extremely hazardous gas whose marker is the smell of rotten eggs. It is colorless and very dangerous when high concentrations are inhaled. Hydrogen sulfide is highly flammable and explodes easily near lit matches, cigarettes, and other sources of spark or heat.
So, where do you find hydrogen sulfide gas (H2S)? H2S presents a particular hazard to those working in confined spaces at or below ground level because it is a naturally occurring hazard. According to the Occupational Safety & Health Administration (OSHA), “Hydrogen sulfide also occurs naturally in sewers, manure pits, well water, oil and gas wells, and volcanoes. Because it is heavier than air, hydrogen sulfide can collect in low-lying and enclosed spaces, such as manholes, sewers, and underground telephone vaults. Its presence makes work in confined spaces potentially very dangerous.” Those most at risk for natural exposure are miners and other personnel involved in energy production, like the oil and gas sector; these industries are also commonly associated with the dangers of confined spaces.
Although only a little irritating at lower concentrations, hydrogen sulfide exposure can result in death. The most likely and dangerous exposure pathway is through inhalation of hydrogen sulfide gas, however, there are some instances where contact is made with the skin. Contact with the skin can result in frostbite or burns.
How do safety professionals mitigate the risk of hydrogen sulfide gas?
Engineering controls are the mechanical means to control the hazard at its source and are the preferred way to protect against hazards. Engineering controls are designed to eliminate the hazard completely, if possible. The primary engineering control used in eliminating hazardous gases is a ventilation system that removes the gas from the work space and makes the area safe for occupancy.
If a hazard cannot be eliminated using engineering controls, administrative controls are added to the hazard-control strategy. Administrative controls are a company’s rules and procedures put in place to protect the health and safety of the workforce.
If engineering and administrative controls are not possible or are not fully effective, you may be required to use personal protective equipment (PPE). For protection against hydrogen sulfide we would be talking about respiratory equipment, eye protection and special gloves and clothing if skin contact is possible. If skin contact is possible, gloves and clothing must be made from a material that cannot be permeated or degraded by hydrogen sulfide and that is insulated to prevent body tissue from freezing.
Hydrogen sulfide often affects the eyes. If someone’s eyes are red or irritated because of exposure to hydrogen sulfide, the first thing you should do is check to see if he or she is wearing contact lenses. If so, remove them at once. Rinse the eyes with plain water for at least 15 minutes, lifting the eyelids as you rinse. Then seek immediate medical attention.
If a worker is exposed to hydrogen sulfide through the skin, wash the skin immediately with water. Contaminated clothing and shoes will be flammable; to reduce the risk of static discharge and ignition, soak contaminated articles of clothing thoroughly while they are still being worn. Then, remove them immediately and wash the skin below thoroughly with water before seeking medical attention.
While you may encounter emergencies like the ones mentioned previously, hazardous exposure to hydrogen sulfide is almost always through inhalation.
Extreme inhalation exposure usually occurs when a worker is unaware of the danger and enters an area with toxic amounts of hydrogen sulfide that cause him or her to collapse. Breathing can be affected very quickly, so it is critical to remove the person to fresh air. When a co-worker has collapsed in an environment where hydrogen sulfide may be present, call 911 or other emergency medical responders. Remove the person to fresh air. If breathing has stopped AND you are trained, begin CPR using universal precautions. Transfer the person promptly to a medical facility.