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H2S Facts

What is H2S?

Hydrogen Sulphide, chemically known as H2S, is a flammable, toxic and extremely dangerous volatile sulphur gas often associated with high pressure and high temperature. In low concentrations H2S smells like rotten eggs, but you should never rely on your sense of smell as exposure in high concentrations, above 100 ppm, will paralyse the olfactory nerve.

Where is H2S gas found?

H2S gas may be encountered during production of oil and gas, oil drilling and well testing operations, sewage and septic pits, in the fishing industry and farming.

What are the effects of H2S gas?

Hydrogen Sulphide is particularly dangerous as the sense of smell is quickly disabled and awareness of the presence of the gas is reduced substantially. Loss of consciousness may occur very suddenly.
When a person breathes in H2S it goes directly through the lungs and into the bloodstream. The H2S reacts with the haemoglobins in the blood and reduces the body's oxygen supply. To protect itself, the body oxidizes (breaks down) the H2S as rapidly as possible into a harmless compound (Sulphate). If the person breathes in so much H2S that the body cannot oxidize all of it, the H2S builds up in the blood and the person becomes poisoned.

H2S facts

  • Colourless transparent gas
  • Rotten egg smell at low concentrations
  • Paralysis of smell at higher concentrations
  • Is heavier than air and will collect in low places
  • Highly toxic, poisonous and flammable
  • Is easily dispersed by the wind

H2S safety reminders

  • Never rely on your sense of smell
  • Familiarize yourself with the location and use of detection and protection equipment
  • Use detection and protective equipment when entering areas where there is a risk of H2S
  • Always use breathing equipment where there is an H2S concentration above what the national legislation allows
  • Always be aware of the wind direction
  • Never work alone in an H2S area (buddy system)
  • Always don full breathing equipment before attempting a rescue in an H2S area
  • Familiarize yourself with the H2S alarm in accordance with the alarm plan