Hydrogen sulfide (H2S) is a gas commonly found during drilling and production of crude oil and natural gas, as well as in sewage treatment plants, public utilities, and sewers. Colorless, flammable, poisonous and corrosive, H2S gas is perceptible by the foul odor of the egg.


With toxicity similar to carbon monoxide that prevents cellular respiration, monitoring and early detection of H2S can mean the difference between life and death.


what is h2s gas

H- compounds are often called hydrides, the term is used rather loosely. The term “hydride” suggests that the H atom has a negative or anionic character, designated as H- and is used when hydrogen forms a compound with a more electropositive element.


The existence of the hydride anion proposed by Gilbert N. By electrolysis of molten lithium hydride (LiH), producing the stoichiometry of hydrogen in the anode.  For hydrides other than groups 1 and 2 metals, the term is quite misleading, given the low electronegativity of hydrogen. The exception in the waters of Group 2 is Be H
2, which is polymeric. AlH- lithium aluminum hydride
4 anions carry hydroxyl centers tightly attached to Al (III).


Gas is a quiet threat, often invisible to the senses of the body. Inhalation is the main route of exposure to hydrogen sulfide. Exposure to high levels of the gas can immediately weaken the sense of smell. Although the smell of H2S is a characteristic, the smell is not a reliable indicator of the presence of H2S gas or for the indication of increasing gas concentrations.


what is h2s
what is h2s


H2 gas irritates the mucous membranes of the body and airways, among others. After exposure, short-term or acute, symptoms may include a headache, nausea, convulsions and eye and skin irritation. Injury to the central nervous system can be immediate and serious after exposure.


Health Effects (Long-term)

Persons with prolonged exposure to sufficiently high levels of H2S to cause unconsciousness may still experience headaches, reduced attention, and motor function.


The lung effects of exposure to H2S gas may not be visible for up to 72 hours after removal from the affected environment. Delayed pulmonary edema, accumulation of excess fluid in the lungs may also occur after exposure to high concentrations.



H2S does not accumulate in the body, but repeated/prolonged exposure to moderate levels can cause low blood pressure, headache, loss of appetite and weight loss.


Prolonged exposure to low levels can cause painful skin rashes and irritated eyes. Repeated exposure to high concentrations of H2S can cause seizures, coma, brain and heart damage, and even death.


Hydrogen gas heavier than air accumulates in low-lying areas of poorly ventilated rooms. In oil and gas applications, acid gas in the presence of air and moisture can form sulfuric acid, which can corrode metals. Equipment of facilities, including internal surfaces of various elements, surfaces with reduced strength and impact resistance, potentially leading to premature failure.



Hydrogen sulfide is a fast-acting poison, acting on many systems in the body. Handy gas sensors are essential for early detection and warning because the body’s senses are not meaningful indicators.


Importantly, you should consider gas detectors, such as the Blackline G7 wireless gas detector, because they warn the live monitoring personnel about the worker’s exposure to H2S. Devices with short response time and robust construction are important for use in harsh conditions where H2S may occur.


In addition, because H2S can anesthetize and make the body unconscious in a short time at high concentrations, it is necessary to connect personal monitoring equipment.



The Occupational Safety and Health Administration (OSHA) defines the Acceptable Exposure Limits (PEL) for H2S gas as follows:

Overall industry ceiling: 20 ppm
General Industry Peak Limit: 50 ppm (up to 10 minutes if there is no other exposure during the change)
8-hour construction limit: 10 ppm
Limit 8 hours in the yard: 10 ppm



People exposed to H2S gas should immediately be removed from the toxic environment.  In severe cases, hospitalization may be necessary.



The Agency for Toxic Substances and Registers of Diseases (ATSDR) recommends to contact a doctor or an emergency visit if any unusual side effects or symptoms occur within 24 hours:

A cough, wheezing, difficulty in breathing, shortness of breath
Pain or tension in the chest
Abdominal pain, vomiting
A headache
Increased redness, pain or pus in the area of skin burns
It is important to be vigilant and avoid self-satisfaction with the safety program.


In inorganic chemistry, the hydrides can also serve as bridging ligands that connect the two metal centers in the coordination complex. This function is particularly common in elements of group 13, especially in boranes (boron hydrides) and aluminum complexes, as well as in concentrated carboranes.



Atomic hydrogen

NASA has investigated the use of atomic hydrogen as a rocket propellant. It can be stored in liquid helium to prevent its recombination with molecular hydrogen.


When helium is evaporated, the atomic hydrogen will be released and combined back to molecular hydrogen. The result would be an intensely hot stream of hydrogen and helium. The launch mass of the rockets can be reduced by 50% thanks to this method.


Most interstellar hydrogen has the form of atomic hydrogen because atoms rarely collide and connect. They are the source of an important waterline with a length of 21 cm in astronomy at 1420 MHz.



 The most frequent hydrogen isotope with an abundance greater than 99.98%. Because the nucleus of this isotope consists only of a single proton, it receives a descriptive but rarely used, the official name for the protium.


Deuterium is not radioactive and does not represent a significant toxic hazard.
Heavy water serves as a neutron moderator and coolant for nuclear reactors. Deuterium is also a potential fuel for commercial fusion.



 known as tritium and contains one proton and two neutrons in its nucleus. It is radioactive, it breaks down into helium from 3 to beta decay with a half-life of 12.32 years.  Glass prevents small amounts of radiation from escaping.

h2 gas is the only element that has different names for its isotopes today. Symbols D and T


H) are sometimes used for deuterium and tritium, but the corresponding symbol for protium, P, is already in use for phosphorus and is therefore not available for protium.  In its nomenclature guidelines, the International Union of Pure and Applied Chemistry (IUPAC) allows any of D, T, 2



what are h2s Discovery and use

In 1671, Robert Boyle discovered and described the reaction between iron filings and dilute acids, resulting in the production of hydrogen.


In 1766, Henry Cavendish was the first to recognize hydrogen gas as a separate substance, calling gas from the reaction “non-flammable air”. He speculated that “flammable air” was essentially identical to the hypothetical substance called “phlogiston” , and further discovery in 1781 that gas produced water after burning.

Antoine-Laurent de Lavoisier

Lavoisier produced hydrogen in his mass preservation experiments by reacting vapor steam with metallic iron through a glowing iron tube heated by fire.


Fe + H2O → FeO + H2
2 Fe + 3 H2O → Fe2O3 + 3 H2
3 Fe + 4 H2O → Fe3O4 + 4 H2
Many metals, such as zirconium, react similarly to water, which leads to the production of hydrogen.


first dissolved

Hydrogen was first dissolved by James Dewar in 1898. Using regenerative cooling and its invention, a vacuum flask. The following year, he produced solid hydrogen. By Ernest Rutherford, Mark Oliphant and Paul Harvick.


François Isaac de Rivaz built the first de Rivaz engine, a combustion engine driven by a mixture of hydrogen and oxygen in 1806. Edward Daniel Clarke invented a hydrogen blower in 1819.


Gas provided an elevator for the first reliable form of air transport after Henri Giffard’s invention of the first hydrogen-controlled aircraft of 1852.  The German Count Ferdinand von Zeppelin promoted the idea of the rigid hydrogen-powered airship, which he later called Zeppelin; the first of them had its maiden flight in 1900.


Regularly scheduled flights began in 1910. And before the outbreak of World War I in August 1914, they transported 35,000 passengers without serious incident. Hydrogen-powered airships served as observation platforms and bombers during the war.


what is h2s
what is h2s


first uninterrupted transatlantic

The first uninterrupted transatlantic passage was carried out by the British aircraft R34 in 1919. Regular passenger services resumed in the 1920s, and the discovery of helium reserves in the United States promised to increase security, but the US government refused to sell gas for this purpose.


Therefore, H2 was used in the airship Hindenburg, which was destroyed during a fire in the air on New Jersey on May 6, 1937.  Ignition of leaking hydrogen is a common cause, but later studies have pointed to the ignition of aluminum covered with fabric by static electricity.


In the same year, the first hydrogen-cooled turbogenerator came into use with hydrogen gas as a cooling medium in the rotor and stator in 1937. At Dayton, Ohio, by Dayton Power & Light Co.,  due to the thermal conductivity of hydrogen, it is currently the most widespread type in this field.



The nickel-hydrogen battery was first used in 1977. Onboard the US Navy Navigation-2 satellite (NTS-2).