Hydrogen Sulfide (H2S)
What is Hydrogen Sulfide?
Hydrogen sulfide is a colorless, flammable gas with a strong rotten-egg odor. It is commonly released from sour crude oil, natural gas reservoirs, and decaying organic matter.
H2S Exposure
A worker opens a storage tank or enters a low-lying area near pooled oil where H2S gas has accumulated, unaware of the odor or danger due to olfactory fatigue.
Hydrogen sulfide is heavier than air and can collect in low-lying areas such as pits, trenches, tanks, barges, and confined spaces. Because it can build up quickly, workers may be exposed without warning if proper monitoring is not used.
Health Risks
Hydrogen sulfide is considered one of the most dangerous gases in the oil and gas industry due to its ability to cause sudden and severe health effects.
- Low concentrations may irritate the eyes, nose, and throat.
- Moderate concentrations can cause dizziness, headache, nausea, and fatigue.
- Higher concentrations may cause loss of smell, making the gas impossible to detect by odor.
- Very high concentrations (above 500 ppm) can cause collapse, coma, respiratory failure, and death within minutes.
- Repeated low-level exposure may damage the nervous system and lungs.
Occupational Exposure Limits
- NIOSH REL: Ceiling of 10 ppm (10-minute).
- OSHA PEL: Ceiling of 20 ppm; one 10-minute peak up to 50 ppm allowed.
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4-5. What is hydrogen sulfide most commonly described as?
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