What is hydrogen sulfide?
Hydrogen sulfide (H2S) is a gas commonly found during drilling and production of crude oil and natural gas, as well as in water treatment plants and wastewater treatment plants. This gas is produced as a result of microbial decomposition of organic matter in the absence of oxygen. H2S gas is colorless, flammable, toxic and corrosive with the smell of rotten eggs. With carbon monoxide-like poisoning, which prevents cellular respiration, early monitoring and detection of H2S can be the difference between life and death.
Impact on safety (short-term)
Gas is a silent threat, often invisible to the body’s senses. Inhalation is the main route of exposure to hydrogen sulfide. Although it may be easily smelled by some people at low concentrations, continuous exposure to even low H2S levels rapidly reduces the sense of smell (olfactory desensitization). Exposure to high amounts of gas can eliminate odor immediately. Although the aroma of H2S is a feature, the odor of H2S does not indicate the presence of H2S gas or an increase in gas concentration.
Stimulates the mucous membranes of the body and respiratory system, among other things. Following short-term or acute exposure, symptoms may include headache, nausea, seizures, and irritation of the eyes and skin. Damage to the central nervous system after exposure can be serious. At high concentrations, only a few breaths are needed to induce anesthesia, coma, respiratory paralysis, seizures, and even death.
Impact on health (long-term)
Those who are exposed to high levels of H2S for long periods of time may experience prolonged anesthesia, along with headaches, decreased attention, and motor function. The pulmonary effects of H2S exposure may not be apparent until 72 hours after removal from the affected environment. Pulmonary edema, the accumulation of excess fluid in the lungs, can also occur as a result of exposure to high concentrations.
H2S does not stay in the body, but frequent, prolonged exposure to moderate levels can cause low blood pressure, headaches, loss of appetite, and weight loss. Prolonged exposure to low levels may cause painful skin damage and eye irritation. Continuous exposure to high levels of H2S over time can cause seizures, coma, brain and heart damage, and even death.
Impact on systems
H2S gas is heavier than air and accumulates in poorly ventilated or near-surface spaces. In oil and gas applications, sour gas (products containing H2S gas) in the presence of air and moisture may form sulfuric acid, which is capable of corroding metals. Installation equipment, including the internal surfaces of various components, is reduced in durability and impact resistance, potentially leading to premature failure.
H2S gas detection
Hydrogen sulfide has a very high toxic activity and affects many systems of the body. Proper gas sensors are essential for early detection and warning because the body’s senses are not reliable indicators. Importantly, gas sensors, like Blackline’s G7 gas sensors, should be given special attention because they warn if personnel are exposed to gas. Devices with fast response times and robust structures are important for use in harsh environments where H2S may be present. In addition, because H2S may cause allergies and anesthetize the body at high concentrations, connected personal monitoring equipment is important.
The Occupational Safety and Health Administration (OSHA) defines the exposure limit (PEL) for H2S as follows:
• Industry ceiling: 20 ppm
Maximum industry peak: 50 ppm (maximum 10 minutes if no other exposure during the shift)
• 8 hour limited construction: 10 ppm
• 8 hour shipbuilding range: 10 ppm
Those exposed to H2S should get out of the toxic environment immediately. Rescuers should be careful when approaching victims who cannot evacuate independently to avoid exposure to H2S. Due to the very rapid toxic effects of the gas, respiratory protection is recommended when entering the H2S environment, such as the safety line. There is no proven antidote to H2S poisoning, but its side effects can be treated or controlled. In severe cases, hospitalization may be necessary.
The Toxic Disease Registry (ATSDR) recommends that you contact your doctor or see an emergency room within 24 hours if you experience any side effects or unusual symptoms:
• Cough, wheezing, difficulty breathing, shortness of breath
• Pain Or chest tightness
• Stomach pain, vomiting
• Increased redness, pain or pus from the skin burn area
It is very important to stay alert and avoid acting arbitrarily for your own safety. Gas tracking equipment should be regularly calibrated and tested frequently .
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