You may have not ever seen, touched or even heard of hydrogen sulfide, but you’ve definitely smelled it. Hydrogen sulfide, also known as H2S, is the rotten-egg-smelling odor that’s produced as organic materials decay. The human body creates hydrogen sulfide as it digests food, which is what causes our “bodily functions” to smell less than rosy. And although passing gas (breaking wind, ripping one, cutting the cheese… whatever wording suits your fancy) has taken center stage in many a joke, hydrogen sulfide in itself is no laughing matter.
In fact, hydrogen sulfide is extremely hazardous. It is a byproduct of industrial and manufacturing processes that can cause health problems and even death when it is inhaled, consumed or comes in contact with skin.
You may be thinking, “How can hydrogen sulfide be so dangerous if our own bodies make it?” But even though we can handle small amounts of exposure to hydrogen sulfide, anything more than the normal amount produced by our bodies can be very harmful to our health.
Hazardous Effects of Hydrogen Sulfide
Hydrogen sulfide almost always occurs as a colorless gas, and exposure happens most often through inhalation. Although hydrogen sulfide can be detected by its rotten egg scent, odor should not be used to confirm its presence since we lose our ability to distinguish an odor after prolonged exposure, and if the concentration is high enough we won’t be able to smell hydrogen sulfide at all.
According to the Agency for Toxic Substances & Disease Registry, people who work in certain industries can be exposed to higher levels of hydrogen sulfide than the general population. These industries include mining, pulp and paper mills, petroleum and natural gas drilling operations, and sewage treatment plants. Individuals have to be especially careful when working in spaces such as basements, manholes, sewers and manure pits because hydrogen sulfide is heavier than air, allowing it to travel across the ground and fill low-lying spaces.
To protect against the harmful levels of hydrogen sulfide, OSHA has set a permissible exposure limit for the gas. A permissible exposure limit (PEL) is the legal limit for worker exposure to a chemical substance. OSHA has set the PEL for hydrogen sulfide at ten parts per million (ppm) over an eight-hour period. Fifty percent of people exposed to hydrogen sulfide for just five minutes at 800 ppm will not survive, and a single breath at 1000 ppm causes immediate death.
Exposure To Low Levels (10 ppm or less)
Common effects of inhaling low concentrations of hydrogen sulfide (10 ppm or less) are burning eyes, coughing and shortness of breath. Repeated or prolonged exposure at low concentration levels can cause eye inflammation, headaches, fatigue, irritability, insomnia, and weight loss.
Exposure To Moderate Levels
Exposure to moderate concentration levels of hydrogen sulfide can result in severe eye irritation, severe respiratory irritation (coughing, difficulty breathing, fluid in lungs), headache, nausea, vomiting, and staggering.
Exposure To High Levels (100 ppm or higher)
Effects of exposure to high levels (100 ppm or higher) of hydrogen sulfide can be serious and life-threatening. Effects include shock, convulsions, inability to breath, rapid unconsciousness, coma, and death.
How To Protect Against Hydrogen Sulfide
There are several ways you can protect against exposure to hydrogen sulfide. One is by using engineering controls such as ventilation systems that remove gas from work spaces. Since hydrogen sulfide is highly flammable, the ventilation system must be explosive-proof.
Another safety measure is to employ administrative controls. Administrative controls can come in the form of company rules for entering, exiting and working in spaces where hydrogen sulfide gas is present. Safety training and gas level testing are also effective administration controls.
A third way to prevent health problems caused by hydrogen sulfide exposure is to use personal protective equipment (PPE). PPE for hydrogen sulfide includes full-face air purifying respirators (APR) for gas amounts up to 100 ppm, and self-contained breathing apparatuses (SCBA) or supplied air lines for gas amounts reaching 100 ppm or higher. If direct skin contact with hydrogen sulfide is possible, workers must wear protective gloves and clothing made from material that cannot be permeated or degraded by the substance.
Emergency Response To Exposure
- Remove contact lenses
- Wash the eyes with water for 15 minutes, lifting the eyelids
- Seek immediate medical attention
- Wash skin immediately
- Soak contaminated clothes and shoes before removing them; wash skin below
- Seek immediate medical attention
- Shut off hydrogen sulfide source if possible
- Use water spray to extinguish flame
- Use water spray to cool off containers, structures or equipment exposed to the fire
- Dry chemical, foam and carbon dioxide are also appropriate extinguishing agents
Mild Inhalation Exposure
- Get to fresh air
- Call 911 or Poison Control
Severe Inhalation Exposure Causing Collapse
- Call 911
- Before helping hurt person, protect yourself by using non-entry procedures if possible, or by wearing a full-face piece breathing apparatus before entering hazardous space
- Get person to fresh air
- Begin CPR if trained
- Transfer immediately to a medical facility
Have you or someone you know ever experienced health problems resulting from hydrogen sulfide exposure? How did the exposure occur, and what could’ve been done to prevent it?
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