Hydrogen Sulfide Information
Hydrogen Sulfide is a colorless, flammable, and poisonous gas. Hydrogen Sulfide can be formed naturally in our environment, typically in low levels, and in many industrial processes. Hydrogen Sulfide does have a strong odor that is commonly characterized as the smell of rotten eggs. Hydrogen Sulfide is also referred to as "sewer gas". The chemical formula if Hydrogen Sulfide is H2S.
In nature H2S can commonly be found in well water where organics have broken down to form H2S in the water. The primary complaint is a foul odor and taste from this water. Higher and potentially hazardous levels of H2S can be found in sewer systems, swamps, and wastewater lagoons.
Industrially H2S is commonly released in high levels from natural gas that contains high contents of H2S. Biogas generators may release up to 1% H2S in the gas streams. Any industrial process where organic material is broken down in the absence of oxygen has the potential to create high levels of H2S. Other industrial applications that may produce H2S are petroleum refineries, coke ovens, tanneries, paper mills, and wastewater treatment
How does H2S harm you?
Even though H2S has a strong odor, olfactory fatigue can deaden the human body's ability to detect unsafe levels of H2S. Do not depend upon your sense of smell to indicate the presence or hazardous concentrations of H2S.
H2S is a poisonous gas, therefore most safety information is based around this potential hazard. Keep in mind, H2S is also flammable, and even explosive in the right conditions. Even if respirators or confined entry equipment is in use, take precautions for the potential of fire and explosion when working in environments that may contain H2S.
H2S is found naturally in the human body at low levels. Therefore at very low levels there is no danger to H2S. High levels of H2S can be deadly. It is believed that 300 - 350 ppm of H2S can be deadly in a very short period of time. In fact the British Army used H2S as a war gas during World War I in two separate occasions.
Health Effects of H2S
Health effects vary with how long, and at what level, you are exposed. Asthmatics may be at greater risk.
- Low concentrations – irritation of eyes, nose, throat, or respiratory system; effects can be delayed.
- Moderate concentrations – more severe eye and respiratory effects, headache, dizziness, nausea, coughing, vomiting and difficulty breathing.
- High concentrations – shock, convulsions, unable to breathe, coma, death; effects can be extremely rapid (within a few breaths).
Tips on measuring H2S
H2S is heavier than air and can sink. Keep in mind that higher levels of H2S may be found in low lying areas
|OSHA General Industry PEL:||20 ppm (Ceiling); 50 ppm (Peak)|
|OSHA Construction PEL:||10 ppm (15 mg/m3) (TWA)|
|OSHA Maritime PEL:||10 ppm (15 mg/m3) (TWA)|
- 0.00047ppm or 0.47 ppb is the odor threshold, the point at which 50% of a human panel can detect the presence of the compound.
- 0.0047 ppm is the recognition threshold, the concentration at which 50% of humans can detect the characteristic odor of hydrogen sulfide normally described as resembling "a rotten egg".
- OSHA has established a permissible exposure limit (PEL) of 10 ppm.
- 10–20 ppm is the borderline concentration for eye irritation.
- 20 ppm is the acceptable ceiling concentration established by OSHA.
- 50 ppm is the acceptable maximum peak above the ceiling concentration for an 8 hour shift, with a maximum duration of 10 minutes.
- 50–100 ppm leads to eye damage.
- At 100–150 ppm the olfactory nerve is paralyzed after a few inhalations, and the sense of smell disappears, often together with awareness of danger.
- 300 ppm and greater leads to pulmanry edemawith the possibility of death.
- 500 – 1000 ppm: Breathing rates speed up followed by temporary suspension of breathing at higher concentrations.
- 800 ppm is the lethal concentration for 50% of humans for 5 minutes exposure
- Concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath.
Our full line of Hydrogen Sulfide (H2S) monitoring solutions are shown below