We're sorry, but OSHAcademy doesn't work properly without JavaScript enabled. Please turn on JavaScript or install a browser that supports Javascript.

901 Oil and Gas Hazard Awareness
Skip to main content

Hydrogen Sulfide Hazards

Hydrogen sulfide (also known as H2S, sewer gas, swamp gas, stink damp, and sour damp) is a colorless gas known for its pungent "rotten egg" odor at low concentrations. It is extremely flammable and highly toxic.

Sign warning those who enter that  it is a Hydrogen Sulfide Hazardous area
Hydrogen Sulfide (H2S) is very hazardous.

Hydrogen sulfide is used or produced in a number of industries, such as:

  • Oil and gas refining
  • Mining
  • Tanning
  • Pulp and paper processing
  • Rayon manufacturing

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.

The health effects of hydrogen sulfide depend on how much H2S a worker breathes and for how long. However, many effects are seen even at low concentrations. Effects range from mild, headaches or eye irritation, to very serious, unconsciousness and death.

Knowledge Check Choose the best answer for the question.

3-8. Where is hydrogen sulfide usually found?