A recent survey revealed less than half of safety professionals in the oil and gas industry knew about new hydrogen sulfide (H2S) exposure limits recommended by the American Conference of Governmental Industrial Hygienists, Occupational Health and Safety magazine reported. The survey, conducted by gas detection firm Drager and the American Society of Safety Engineers, said 53 percent of safety professionals were unaware of the new standards that suggested a threshold limit value of 1 parts per million (ppm) and a short term exposure level of 5 ppm. This survey may indicate that oil and gas companies could be unprepared for H2S exposure if they do not employ engineering controls like air cleaners.
Dangers of H2S and health effects
The U.S. Occupational Safety and Health Administration said H2S is one of the major causes of gas inhalation deaths in the workplace, citing data from the U.S. Bureau of Labor Statistics that show hydrogen sulfide exposure resulted in 60 deaths between 2001 and 2010.
H2S is a colorless and highly flammable gas that can cause severe health effects or even death after it is inhaled. Oil and gas workers may become exposed to H2S during crude petroleum and natural gas operations, such as during oil and gas drilling and refining.
As a gas, the health effects of H2S can revolve around the respiratory system and the symptoms of toxic gas exposure depend on the level of concentration and duration of exposure. For example, low concentrations can result in eye, nose and throat irritation and sustained exposure can cause insomnia, headache or fatigue. Moderate to severe levels of concentration can also cause difficulty in breathing and coma.
“Hydrogen sulfide is both an irritant and a chemical asphyxiant with effects on both oxygen utilization and the central nervous system,” OSHA said.
While H2S is distinct for its smell akin to rotten eggs, OSHA warns that this gas poses a danger to workers even when they can’t detect an odor.
“However, with continuous low-level exposure, or at high concentrations, a person loses his/her ability to smell the gas even though it is still present (olfactory fatigue),” according to OSHA. “This can happen very rapidly and at high concentrations, the ability to smell the gas can be lost instantaneously.”
Precautions to reduce H2S exposure
Since OSHA cautions workers not to depend on their ability to smell the gas to determine whether H2S is in the workplace, OSHA recommends that employers test the air for the presence of H2S before allowing workers to enter these areas. In the event that H2S is detected, employers should continually ventilate the area to extract the gas.
Oil and gas companies can choose air filtration systems that are made for hazardous gas extraction. Employers implement high efficiency particle air (HEPA) filters, which can help reduce the risk of inhalation of toxic gases. By concentrating on worker health in regard to respiratory protection, companies can improve their chances of complying with H2S exposure limits based on the American Conference of Governmental Industrial Hygienists’ recommendations.
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