The Safety Blog on Safety Tips for the Workplace

H₂S exposure chart is a very important tool to know the toxicity level of H₂S or hyrogen sulfide.

As a very toxic gas, H₂S is very deadly since it can kill person in a few seconds if the person is exposed to a high level of H₂S gas.

This gas has a specific smell like a rotten egg. Unfortunately, you cannot see the gas, since it is a colorless gas.

H₂S or hydrogen sulfide is also known as sewer gas, sour gas, stink damp, and hydrosulfuric acid.

H₂S exposure chart serves as a basic reference for workers and employers about the dangerous level of H₂S and to prevent H₂S poisoning in the workplace.

But before seeing the chart, we will learn a common list of H₂S gas sources in the workplace, the safety hazards, and workplace accident statistics that involving H₂S.

H₂S Sources In The Workplace

You must be able to identify the H₂S sources in your workplace in order to control the hazards and prevent its exposure.

When you finish identifying these sources, then the next step that you need to do is to let workers know about their existence.

You can use H₂S warning signs or proper safety slogans. Or you can also provide the sources in the hazard mapping in your work area.

So, where can H₂S be found in the workplace? Here are the common sources of H₂S that generally found in the workplace:

1. H₂S is a by-product of wood breaking down into pulp in the pulp and paper industry
2. In the construction industry, during excavation work in swamps or old landfills, hydrogen sulfide can be obtained
3. H₂S can also come from sewers, sewage treatment plants, manure tanks, and other areas where organic material breaks down without oxygen
4. H₂S can be found in the refinery industry, especially at oil and gas wells
5. H₂S may be a by-product of an iron smelting plant
6. In an ethylene generation plant where ethanol is converted into ethylene gas, H₂S is a by-product.
7. Rayon textile production acts as another hydrogen sulfide source in the industry
8. Food processing is another source of H₂S

What Are The Hazards of H₂S?

After knowing the common sources of H₂S, then you need to know the hazards of this gas.

As I said before that H₂S exposure can be deadly. It depends on the level or concentration of H₂S you are exposed to.

Accoring to the Safety Data Sheet (SDS) of H₂S, the hazards of H₂S are

• OSHA considers this compound as a hazardous material (29 CFR 1910.1200)
• It is an extremely flammable gas, category-
• H₂S is a very toxic gas, category-2, where the target organ is the respiratory tract
• It may form explosive mixtures with air
• Fatal if inhaled
• It is very toxic to aquatic life
• It can cause irritation on the eyes, dizziness, nausea, and death
• It is also a chemical asphyxiant, which can inhibit the flow of oxygen from our bloodstream to our cells

H₂S Work-Related Accident Statistics

In the period of 2011-2017, there were 46 fatalities caused by hydrogen sulfide inhalation, as reported by the US Bureau of Labour Statistics.

It was the second top cause after carbon monoxide inhalation.

H₂S Exposure Charts

H₂S exposure chart is a chart that shows a relation between hydrogen sulfide level or concentration in the air and their effects to human health.

The higher the concentration, the worst the effect will be.

Please refer to the table below for the exposure chart.

Concentration (ppm)	Short Term Symptoms/Effects
1000-2000	Nearly instant death
700-1000	Rapid unconsciousness, “knockdown” or immediate collapse within 1 to 2 breaths, breathing stops. Death within minutes.
500-700	Staggering, collapse in 5 minutes. Serious damage to the eyes in 30 minutes. Death after 30-60 minutes.
200-300	Marked conjunctivitis and respiratory tract irritation after 1 hour. Pulmonary edema (fluids in lungs) may occur from prolonged exposure.
100	IDLH – Immediately Dangerous to Life and Health Leave area and get to your safety zone Coughing, eye irritation, loss of sense of smell Altered breathing, drowsiness after 15-30 minutes Throat irritation after 1 hour Gradual increase in severity of symptoms over several hours. Death may occur after 48 hours
50-100	Slight conjunctivitis (eye irritation and redness). Respiratory tract irritation after 1 hour. May cause digestive upset and loss of appetite.
20	Possible fatigue, loss of appetite, headache, irritability, poor memory, dizziness.
2-5	Prolonged exposure may cause nausea, tearing of the eyes, headaches or loss of sleep. Airway problems (bronchial constriction) in some asthma patients.
0.01-1.5	Odor threshold (when rotten egg smell is first noticeable to some). Odor becomes more offensive at 3-5 ppm. Above 30 ppm, odor described as sweet or sickeningly sweet.
0.00011- 0.00033	Typical background concentrations

Conclusion

H₂S is a very toxic gas that can cause severe effect to death. So, it is very important to know the H₂S exposure charts to understand the relation between their concentration and effects.