Why is H2S so Dangerous?

H2s dangerous

Anaerobic digestion technology has many merits, but some of its by-products need to be addressed properly. One of them is hydrogen sulfide (H2S), which can pose a great threat to both humans and environment. The importance of its removal can’t be underestimated and large systems that encounter this problem are required by law to facilitate H2S removal for biogas operations for several reasons, some of which are stated below.

What Is H2S?

What is H2S

Hydrogen sulfide is a toxic gas produced by sulfate-reducing bacteria under anaerobic conditions. If this definition is confusing, you should focus on the fact that it presents problems in the anaerobic digestion process for several reasons, such as contributing to foul odors and sulfur dioxide(SO2) emission when combusted. Also, H2S creates a corrosive environment when moisture is present and can compromise the quality and effectiveness of fuel delivery systems. That is why it’s important to have it removed properly.

How does it impact safety?


Gas is a silent threat, which is often unregistered by our senses and people are exposed to it mainly by inhaling it. Also, even though some people can smell it at small concentrations, their continuous exposures to even low levels of H2S easily deadens the sense of smell quickly, while exposure to high levels of the gas deadens the sense of smell almost instantly. The problem is that despite the characteristic scent of H2S, smell is not a reliable indicator of H2Sgas presence.

H2S irritates the mucous membranes of the body and the respiratory tract, which can easily result in a headache, nausea, convulsions, and eye and skin irritation. Exposure to it can also lead to the central nervous system suffering serious injuries. Even worse, at high concentrations, all it takes are a few breaths to induce unconsciousness, coma, respiratory paralysis, seizures, or even death. Prolonged exposure to high levels of this gas may also lead to reduced attention span and motor functions. Delayed pulmonary edema, a build-up of excess fluid in the lungs, may also occur following exposure to high concentrations.

Impact on facilities


Since it’s heavier than air, H2S accumulates in low lying areas of poorly ventilated spaces. What also happens is that in oil and gas applications, sour gas (products containing H2S gas) reacts with air and moisture to form sulfuric acid, which can corrode metals. That is another reason why efficient hydrogen sulfide treatment should include the best possible equipment and people who know how to do the job.

Impact on the environment

Environment impact

Apart from affecting people and facilities, H2S has detrimental effects on the environment as well. It is an environmental pollutant in and of itself, which emits sulfur dioxide (SO2), which is dangerous to trees, plants and animals when present in high concentrations. It damages foliage and stunts growth, as well contributes to acid rain, thus harming fragile ecosystems. SOis also known to react with other compounds in the atmosphere, forming fine particles that create a haze, reduce visibility and deposit on structures, including statues and monuments, staining and damaging them.



In order to detect this fast-acting poison, wearable gas sensors need to be used, since the body’s sensors are not the most reliable indicators. Such devices are used not only to detect, but also alert people of exposure to H2S. What is also important is to have devices which provide fast response and are of sturdy construction, since they might be required to operate in harsh conditions. Also, because H2Scan desensitize and render the body unconscious, it’s vital to use connected personal monitoring equipment. Needless to say, it’s highly recommended that all such equipment is manufactured by renowned companies, since the quality of the detection equipment is vital for prompt and proper reaction.



To being with, those exposed to this gas have to be removed from the toxic environment without delay. However, rescuers need to be careful when approaching victims as to not be harmed themselves by H2S exposure. When entering an H2S environment, it’s recommended to use respiratory protection and a safety line, due to the very rapid toxic effects of the gas. So far, no proven antidotes to H2S gas poisoning have been known to exist, but side-effects and symptoms can be treated and managed, though severe cases of poisoning may require hospitalization.

As you can see, hydrogen sulfide is potentially very dangerous to humans, animals, plants and equipment in large industrial facilities, which is why countries around the world have passed various laws and regulations related to dealing with this threat. Adhering to these regulations will not only help you keep everyone safe, but also prevent further possible damage to the environment, which might have many long-term consequences. Therefore, it’s in everyone’s interest to know what this poisonous gas can cause and how to deal with being exposed to it.

The views expressed in this article are those of the authors and do not necessarily reflect the views or policies of The World Financial Review.