h2s gas icon


Hydrogen Sulfide (H2S)


Hydrogen Sulfide, H2S is a highly toxic gas that has a distinctive and unpleasant rotten-egg smell. It is a colorless gas, that can occur naturally in the air via various crude or natural oil sources, volcanic gases, and spring waters. Trace amounts of H2S can be found in the atmosphere which is generally not harmful.

Hydrogen Sulfide
in the Environment


Hydrogen Sulfide is produced by bacterial breakage of animal, plant, and human waste. It can be produced by volcanic gases, and natural springs as well. H2S gas dissolved in the soil helps in the root growth of plants.


hydrogen sulfide in the environment


“The primary target organ of hydrogen sulfide poisoning is the respiratory system. Once inhaled, hydrogen sulfide is quickly absorbed by the lungs. This may result in cardiac arrest or even death since it affects the neurological and cardiac tissues. The most well-known symptom of hydrogen sulfide poisoning is sudden death among sewage workers. All exposures to H2S should be avoided because they have severe harmful effects.”
– Saiyed, H N.  Indian Journal of Medical Research; New Delhi

Sources of Hydrogen Sulphide Gas

Hydrogen sulphide gas is produced naturally from decaying organic matter and industrial processes, and can be lethal in high concentrations. Following are some of its potential sources:


Natural Sources

h2s from volcanic gases

Volcanic Gases

During volcanic activity, volcanoes naturally release H2S gas through their vents and cracks.

h2s from gas wells

Gas wells

H2S gas may be present in natural gas wells and could be released during production and drilling.

h2s from natural reservoirs

Natural Gas Reservoirs

It may be present in natural gas reservoirs, and can be discharged during processing and extraction.

h2s gas from natural springs

Natural Springs

As sulfur-containing minerals react with water to produce H2S gas, natural springs can be a source of H2S gas.

h2s from crude petroleum

Crude Petroleum

Crude petroleum may produce H2S gas during extraction and processing, posing health and safety issues.

Industrial Sources

h2s from sewage treatment plants

Sewage Treatment

From the decomposition of the organic content in wastewater, sewage treatment plants might emit H2S gas.

h2s from refineries


Refineries can generate H2S gas by the processing of sulphur-containing crude oil. The gas can pose threat to  one’s health and safety.

h2s from kraft paper mills

Kraft Paper Mills

In the pulping process, kraft paper mills use chemicals based on sulphur, which produces H2S gas as a byproduct

h2s from food processing

Food Processing

Food processing units that utilize sulphurs and sulphuric acid emit H2S gas into the surrounding environment.

h2s from water treatment plants

Wastewater Treatment

Wastewater treatment plants produce H2S gas during the breakdown of organic matter.

Hydrogen Sulphide gas
Health Hazards


H2S is extremely hazardous for workers, laborers, miners, etc. that have to work with this gas continuously, on a regular basis. It is a highly flammable gas and can react with steel at ambient temperature. This makes handling, storage, transportation, and working with the gas very laborious and demanding.


h2s health hazards



Keeping in mind the acute health hazards of occupational hydrogen sulfide emissions, the following table shows the levels of H2S in PPM by the Industrial Safety and Chemical Hazards Sectional Committee.

  • H2S levels
  • Duration of exposure
15 min >15 min >1h-4h >4-8ht
10 - - Eye irritation Maximum tolerable
concentration for prolonged exposure
50-100 Loss of olfactory>
Eye irritation Eye and
bronchial irritation
Serious respiratory
distress and asthenia
150-250 Eye and skin irritation Eye and bronchial irritation Serious respiratory
distress and asthenia
Danger in case of
continuous exposure
300-400 Loss of olfactory
perception eye
Severe respiratory distress
acute asthenia
Pulmonary edema &
risk of death
Pulmonary edema &
risk of death
500-1,000 Loss of consciousness
respiratory distress
Risk of pulmonary
edema and death
- -
  • >1,000
  • Immediate loss of consciousness and
    respiratory distress


Preventive measures if you are
working with Hydrogen Sulphide

storage space

Monitor your storage space

Make sure to monitor the storage area in real time so that any spillages or leakages can be identified and immediate strategies can be adopted.

maintain temperature

Keep an eye on the temperature

Maintain the temperature where the gas is stored as the higher temperature can decompose the gas’s elements that can cause the bursting of the storage container.

no smoking area

No smoking near storage area

The area where the gas is stored should be “NO SMOKING AREA” as the gas is highly flammable. A small spark can be deadly if there is hydrogen sulphide gas in the air.

proper ventilation

Ventilation is the key

The area must be highly ventilated. Hydrogen sulfide is heavier than air. It can easily travel to any source of ignition. That is why ventilation is important in storage areas.

precautionary measure

Use precautionary measure

Protective gear must be used while handling the gas such as safety goggles, airtight clothing, respiratory protection gear, etc. Prevent direct skin contact.

fire extinguisher

Ready to use fire safety

Keep a fire extinguisher in hand if any accident happens. There are high chances of fire as the hydrogen sulphide gas is highly flammable.

How To Detect H2S Gas

An air quality monitor/sensor can detect H2S gas and furnish real-time information on its concentration in the air. This data can aid in making well-informed decisions to safeguard public health and the environment.

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