Hydrogen sulfide safety training

Hydrogen sulfide safety training

Hydrogen sulfide safety training is essential to you because this substance can harm you. Learn all the basics of this dangerous and toxic gas, while sitting in the comfort of your home or office. Occupational safety is very important to workers working with H2S hazards and this Hydrogen sulfide safety training will help you manage them. Many worker deaths have occurred in the past, especially in the energy industry (mainly in oil and gas) because precautions to take where H2S is likely to be present are not known.

If you are an engineer, labor, technician, supervisor, manager, or safety manager working in the oil and gas industry, or in the chemical and petrochemical manufacturing industry, or in pharmaceutical manufacturing, metal processing, or other industries where H2S is present, then you MUST know what precautions to take, how to work in an area that may see a sudden onset of H2S, etc.

Hydrogen sulfide (H2S) is a gas commonly found during the drilling and production of crude oil and natural gas, as well as in wastewater treatment and utility and sewer facilities.  Industrial sources of hydrogen sulfide include oil refineries, natural gas plants, petrochemical plants, coke oven plants, food processing plants, and tanneries.

This makes practical and efficient Hydrogen sulfide safety training of great importance so that critical exposure of personnel is minimized as far as possible and additionally know how to react appropriately in emergencies, reducing the probability of occurrence of tragic episodes.

Hydrogen sulfide safety training
Hydrogen sulfide safety training

Goals of Hydrogen sulfide safety training

Provide readers with information that allows them to:

  • Know the properties of H2S.
  • H2S detection.
  • Understand and apply safe work procedures in the event of the possible presence of H2S.
  • Plan and prepare jobs that involve the presence of H2S.

At the end of the training, you will be able to work and deal with unwanted events in environments where there is the possibility of H2S presence.

  • Health Hazards from H2S Exposure
  • Electronic Monitors
  • Safe use of SCBA

What are some characteristics of h2s gas

Its slightly sweet taste and the particular smell of rotten eggs. It occurs naturally as a byproduct of decomposition. The density of Hydrogen Sulfide (H₂S) is greater than air and it tends to accumulate in low places. Hydrogen sulfide is a colourless, noxious gas that is generated under certain conditions, called anaerobic conditions or septicity, where there is no oxygen.

One of the disadvantages of relying on the sense of smell to detect the presence of hydrogen sulfide is that above a certain concentration, hydrogen sulfide anaesthetizes the olfactory nerve, making it “disappear” and completely undetectable. Exposure to a low concentration of the gas can burn the respiratory tract and cause swelling around the eyes.

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Hydrogen sulfide is a highly toxic gas. It reacts with enzymes present in the bloodstream that inhibit cellular respiration. In other words, a high concentration of hydrogen sulfide can cause the lungs to collapse. In adults, it is lethal from 300 ppm (parts per million). Under certain conditions, in a confined space, hydrogen sulfide can be instantly fatal.

H2S gas is colourless, flammable, poisonous and corrosive. It is 6 times more lethal than Carbon Monoxide and half as lethal as Hydrogen Cyanide. When it appears as free gas is when it is the most dangerous. With toxicity similar to that of carbon monoxide, which prevents cellular respiration, monitoring and early detection of H2S could mean the difference between life and death.

Hydrogen sulfide is a compound whose formula is (H2S).

  • 2 hydrogen atoms.
  • 1 sulfur atom.


The main properties of hydrogen sulfide (H2S) are:

  • Density: 1.189 g/cm 3.
  • Molar mass: 34.081 g/mol.
  • Melting point: -82.4 °C.
  • Boiling point: -60.7 °C

Hydrogen sulfide safety training for awareness

However, on some occasions, it can be released in the liquid waste of an industry or as a result of a natural event. When released as a gas, it remains in the atmosphere for an average of 18 hours. In this period, hydrogen sulfide can be transformed into sulfur dioxide and sulfuric acid. Hydrogen sulfide is soluble in water.

Hydrogen sulfide safety training
Hydrogen sulfide safety training

When a substance is released from a large area, for example from an industrial plant, or a container such as a barrel or a bottle, the substance enters the environment. This release only sometimes leads to exposure. You can be exposed to a substance only when you come in contact with it—by breathing in, eating, or drinking the substance, or by skin contact.

Much lower amounts can enter through the skin. Hydrogen sulfide is a gas, so it is unlikely that you would be exposed by swallowing it. When you breathe air that contains hydrogen sulfide or when hydrogen sulfide comes in contact with your skin, it enters your bloodstream and is distributed throughout your body. In the body, hydrogen sulfide is mainly converted to sulfate and is excreted in the urine.

Hydrogen sulfide levels in air and water are typically low. The amount of hydrogen sulfide in the air in the United States is 0.11 to 0.33 parts per billion (ppb) (one-thousandth of a ppm). In unpopulated areas of the United States, concentrations between 0.02 and 0.07 ppb have been detected.

The amount of hydrogen sulfide in the surface water is low because hydrogen sulfide evaporates easily. Hydrogen sulfide concentrations in groundwater are generally less than 1 ppm; however, Sulfur concentrations measured in surface water and wastewater have ranged from just under 1 ppm to as high as 5 ppm.

Household exposures to hydrogen sulfide can occur from the improper use of drain cleaning materials. Hydrogen sulfide can be found in well water and can form in water heaters, giving the water a rotten egg odour. Cigarette smoke and emissions from gasoline-powered vehicles contain hydrogen sulfide.

Hydrogen sulfide safety training
Hydrogen sulfide safety training

People who work in wastewater treatment plants, oil and gas and petrochemical industries may be exposed to higher levels of hydrogen sulfide than the general sector. Workers on farms with compost storage pits or in landfills may be exposed to higher levels of hydrogen sulfide than the general population.

As a member of the general public, you could be exposed to higher than normal amounts of hydrogen sulfide if you live near a wastewater treatment plant, near where oil and natural gas drilling operations are conducted, near a farm where there are cattle or compost is stored or near a landfill.

Hydrogen sulfide – the gas known for its foul odour, responsible for flatulence and bad breath – may serve to accelerate the development of liver cells from dental pulp stem cells. Hydrogen sulfide, which the human body generates in small amounts, is however also produced by bacteria and, in large amounts, can be highly toxic.

Your body makes small amounts of hydrogen sulfide. Hydrogen sulfide is produced by naturally occurring bacteria in the mouth and is partly responsible for bad breath. The degradation of sulfur-containing proteins by bacteria in the gastrointestinal tract also produces hydrogen sulfide.

What effect does hydrogen sulfide have on the body?

Exposure to low concentrations of hydrogen sulfide may cause eye, nose, or throat irritation. It can also cause shortness of breath in people with asthma.  In most cases, the person seems to regain consciousness without suffering other effects.

However, permanent or long-term effects may occur in many individuals, such as headaches, lapses in concentration and poor memory.  There is very little information about the health problems that could occur from eating something that contains hydrogen sulfide. No cases of people intoxicated in this way have been described. Some pigs that ate feed containing hydrogen sulfide had diarrhoea for a few days and lost weight after about 105 days.

Hydrogen sulfide safety training
Hydrogen sulfide safety training

Scientists have little information about what happens when hydrogen sulfide comes in contact with the skin. However, it is known that care must be taken to avoid freezing the skin. Hydrogen sulfide has not been shown to cause cancer in humans, and its possible ability to cause cancer in animals has not been thoroughly studied. Hydrogen sulfide has not been classified as to its ability to cause cancer.

High concentration blocks the transfer of oxygen to the blood cells and causes paralysis of the respiratory system.

Effects of short-term exposure

Rapid evaporation of the liquid may cause frostbite, and irritates the eyes and respiratory tract. Inhalation of this gas can cause pulmonary edema. Effects may not appear immediately. Medical surveillance is recommended. The substance may affect the central nervous system. Exposure could cause unconsciousness. Exposure could cause death.

Hydrogen sulfide safety data sheet

Exposure limit






·       General Industry Ceiling Limit: 20 ppm

·       General Industry Peak Limit: 50 ppm (up to 10 minutes if no other exposure during shift)

·       Construction 8-hour Limit: 10 ppm

·       Shipyard 8-hour limit: 10 ppm

Health effects

Exposer limit (ppm)Health effects
0.008-0.2Respiratory threshold- rotten egg odour detected
2 TO 5Repeated exposure causes nausea, tearing, headache,
10PEL (OSHA) 8-hour TWA
15STEL(OSHA) 15 minutes TWA
20Odour of a gas leak, tolerance for a few hours without damage, poor memory, dizziness, loss of appetite
20 TO 50Eye irritation, Prolonged exposure may cause pharyngitis or bronchitis.
50 TO 150Prolonged exposure may cause pharyngitis or bronchitis and conjunctivitis and eye pain. Upper respiratory tract irritation
The sensation of loss of smell.
200 to 300Life-threatening pulmonary oedema
500 to 700Collapse in 5 minutes, death within 1 hour
700 to 1000Death within minutes

Can you be tested for hydrogen sulfide poisoning?

A more reliable test to determine if you have been exposed to hydrogen sulfide is to measure thiosulfate levels in your urine. This test must be carried out within 12 hours after exposure. These tests require special equipment that is only sometimes available in a doctor’s office. The samples may be sent to a special laboratory for analysis.

These tests can tell if you were exposed to hydrogen sulfide, but they cannot tell the exact amount of hydrogen sulfide you were exposed to or whether adverse effects will occur. Exposure to high levels of hydrogen sulfide can cause long-term effects on the nervous system.

What is a regulatory agency with regulations addressing hydrogen sulfide?

Regulations can be enforced by law. Occupational Safety and Health Administration external icon (OSHA), and the US Food and Drug Administration. External icons (FDA) are some federal agencies that develop regulations for toxic substances. The recommendations provide valuable instructions to protect public health, but cannot be enforced by law.

The Agency for Toxic Substances and Disease Registry (ATSDR) and the National Institute for Occupational Safety and Health (NIOSH) of the Centers for Disease Control and Prevention (CDC) are two federal agencies that provide information and recommendation for hydrogen sulfide.

Regulations and recommendations may be expressed as “no-exceed levels” – in other words, levels of the toxicant in air, water, soil, or food that do not exceed critical stories that are generally based on levels that affect humans and animals.  The recommendations and regulations are periodically updated as additional information becomes available. For the latest information, check with the federal agency or organization that issues it. The followings are some regulations and recommendations for hydrogen sulfide:

Is h2s the cause of corrosion inhibitor?

One of the characteristics of hydrogen sulfide is that it causes corrosion in sewage structures and wastewater treatment plants. In the humid and warm environments of the sewage network, H2S is oxidized to sulfuric acid. This sulfuric acid is corrosive and attacks wastewater and wastewater treatment plants.

It attacks concrete, copper, steel and silver that may be in treatment tanks, buildings and electrical equipment. If preventive measures are not taken, eventually the pipes exposed to this corrosion can break. Corrosion particularly affects submerged parts of structures in drains or wastewater treatment plants. The rate of corrosion will depend on the amount of H2S that has formed and the level of preventive treatment.

H2S cause fire and explosion           

Extremely flammable gas, air mixers can be explosive. Avoid open flames, NO sparks and NO smoking. Closed system, ventilation, explosion-proof electrical and lighting equipment. Avoid the generation of electrostatic charges (e.g. by grounding).

Intense heating may cause violent combustion or explosion. Decomposes on burning. This produces toxic gases of sulfur oxides. Reacts with strong oxidants. This creates a fire and explosion hazard. Attacks many metals and some plastics. LEL of H2S is 4%, and UEL – is 46%.

H2S monitor

Continuous monitoring, early detection, and evaluation of the concentrations of hydrogen sulfide present are crucial factors. H₂S detectors help ensure worker safety in hazardous environments. They are designed to alert employees when a previously set minimum or maximum H₂S set point is reached.

Hydrogen sulfide safety training
Hydrogen sulfide safety training

Users will adjust the settings based on the permissible exposure limits (PEL) of the environment in question. PEL is the maximum amount of a chemical that a worker may be exposed to according to the latest regulations set by the Occupational Safety and Health Administration (OSHA).

The main motto of Hydrogen sulfide safety training is that when the presence of H₂S is detected there is no time to lose, every second counts. The respirators and their proper use are essential to protect the lives of workers.

What breathing apparatus for H2S?

The self-contained breathing apparatus SCBA can be widely applied in the place of H2S, and high or unknown concentrations of toxic gases that endanger human health. The function of this equipment is to preserve the health and life of people who operate in environments where the air is not breathable.

Hydrogen sulfide safety training
Hydrogen sulfide safety training

For exposures of 100 ppm or greater, use a self-contained breathing apparatus (SCBA) with a minimum service life of thirty minutes or a combination pressure-demand supplied-air respirator with a full facepiece. Exposures at 100 ppm or higher are considered immediately dangerous to life and health (IDLH). (OSHA)

For this reason, Hydrogen sulfide safety training recommends to must comply with a set of recommendations aimed at mitigating the risks to users. These are:

  • Anyone who is going to use SCBA must undergo a medical check-up beforehand. Without medical certification, one of these devices should not be used.
  • In no case can the mask be removed from the face while the person is in a contaminated or rarefied environment.
  • The person who is going to use the equipment must be trained to verify the amount of air available.
  • The equipment must be periodically tested to verify its proper functioning.
  • Before each use, you must verify that the pressure gauge works correctly; it depends on this piece that you know precisely the amount of air you have.
  • Before each use, the condition of the straps and harness must be checked.
  • This is safety equipment, and while not in use you should keep it free of contaminants.




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