Hydrogen Sulfide, or H2S, is a naturally occurring gas. H2S is generated in sewers, well water, and oil and gas wells. However, it is also produced as a bi-product in many industrial processes; such as gas refinement, tanning, mining, and pulp and paper processing. Due to its mass (Hydrogen Sulfide is heavier than air) H2S will gather in enclosed spaces. For example, opening a manhole cover will often release the ‘rotten egg’ smell associated with Hydrogen Sulfide. H2S collects in the sewer system, and fills manholes.
The Danger of Hydrogen Sulfide
H2S is dangerous for a few reasons. First, because it is such a common gas there are many instances where employees may come in contact with it. Secondly, Hydrogen Sulfide can harmful at low levels; though more serious effects aren’t noticed until higher levels of exposure.
The level of exposure determines the symptoms experienced. Employees exposed to low levels of Hydrogen Sulfide may experience eye irritation, nausea, or headaches. These effects are noticed starting when gas levels are between 2 and 5 parts per million. Once levels reach 20ppm or higher, then the effects of Hydrogen Sulfide begin to intensify. After one hour of exposure individuals may begin to feel dizzy, have memory loss, and respiratory tract irritation. When gas levels reach 500ppm or higher then individuals are at risk of death. After 5 minutes of exposure to levels of 500ppm individuals will collapse within 5 minutes, and death will occur in as few as 30 minutes. Gas levels greater than 700ppm will bring near instantaneous loss of consciousness after a breath or two, and death follows shortly after.
Currently, the Occupational Safety and Health Administration have regulations keeping exposure to Hydrogen Sulfide at a minimum. For General Industry the peak limit is 50ppm, while Shipyard and Construction industries are regulated to 10ppm. Overall, the Recommended Exposure Limit set by OSHA is 10ppm for a 10 minute time of exposure. These are enforceable limits.
Hazards beyond Exposure
Hydrogen Sulfide presents hazards on fronts other than inhalation and exposure. First, H2S is extremely flammable. Handling Hydrogen Sulfide without care or operating equipment that could spark near a collection of Hydrogen Sulfide may result in an explosion that could seriously injure or even kill a worker. Additionally, rapid unconsciousness caused by exposures to gas levels over 500ppm could result in falls that could cause trauma. For example, an employee climbing down into a manhole could pass out and fall upwards of 20 feet into the sewer.
Mitigating Exposure and Improving Safety
Reducing circumstances where employees may be exposed to significant levels of Hydrogen Sulfide is the first step in reducing accidents and injuries. Assessing worksites, job functions, and duties of employees to determine areas and times when exposure to Hydrogen Sulfide could occur is key to preventing exposures.
Companies and industries already require gas testing, paperwork, and other protocols before entering into and working in enclosed and confined spaces. Employers need to make sure their employees are following protocol, filing necessary paperwork, and carrying out essential gas testing before entering into spaces that could be filled with gasses like Hydrogen Sulfide. Ensure testing equipment is being operated by the correct personnel and that the equipment is fully functioning and gives an accurate readout.
Finally, employees need to listen to their bodies. The ‘rotten egg’ smell caused by Hydrogen Sulfide is detectable at less than 5 parts per million. Additionally, light headedness, headaches, and nausea are all caused by prolonged exposure to low levels of H2S. These symptoms are a sign that something is wrong. If you are experiencing these symptoms and they are progressing then it is time to remove yourself from the area of exposure.
Employers, Hydrogen Sulfide is a commonly occurring gas which Employees could encounter in a variety of situations. Ensure your employees are trained and aware of the effects of Hydrogen Sulfide. Education and preparation is the best way to present accidents and injury.
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