Deer Park, Tx – The deadly gas that killed two maintenance workers at the Pemex refinery in Deer Park is hydrogen sulfide. When it was leaked into the air Thursday afternoon, more than three dozen people inhaled it - 35 of them were treated at the site.
RELATED: Two dead, 35 people treated after chemical release at Pemex plant in Deer Park
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Hydrogen sulfide occurs in nature and is also produced and used in different industries.
In nature, it occurs naturally in sewers, manure pits, well water, oil and gas wells and volcanoes.
Man-made hydrogen sulfide can be gas or liquid. It’s used for oil and gas refining, mining, tanning, pulp and paper processing and rayon manufacturing.
It’s highly flammable and toxic. The gas is colorless and smells like rotten eggs when you first come into contact with it.
In the U.S., hydrogen sulfide is one of the leading causes of workplace gas inhalation deaths, according to the Occupational Health and Safety Administration (OSHA).
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Why is it so deadly?
5 reasons according to OSHA:
- It is highly flammable and toxic, even at low concentrations.
- It is heavier than air and may travel along the ground.
- It can build up in low-lying areas, and in confined spaces (including enclosed, poorly ventilated areas, such as manure pits, sewers, manholes, and underground vaults).
- After a while at low or more quickly at high concentrations, you can no longer smell it to warn you it’s there.
- It can quickly, almost immediately, overcome unprepared workers, including rescue workers.
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What happens if you inhale it?
There are limits of 10 parts per million (ppm) for workers, according to OSHA.
Symptoms and their effects:
- Up to 1.5 ppm = Odor threshold when you might first notice the rotten egg smell.
- 2 - 5 ppm = Prolonged exposure at this level can cause nausea, your eyes might tear up and you could experience headaches or have trouble sleeping. Some asthma patients can start to feel bronchial constriction.
- 20 ppm = Possible fatigue, loss of appetite, headache, irritability, poor memory, dizziness.
- 50 - 100 ppm = Slight conjunctivitis (“gas eye”) and respiratory tract irritation after 1 hour. May cause digestive upset and loss of appetite.
- 100 ppm = Coughing, eye irritation, loss of smell after 2-15 minutes (olfactory fatigue). Altered breathing, and 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.
- 100 - 150 ppm = Loss of smell (olfactory fatigue or paralysis).
- 200 - 300 ppm = Marked conjunctivitis and respiratory tract irritation after 1 hour. Pulmonary edema may occur from prolonged exposure.
- 500 - 700 ppm = Staggering, collapse in 5 minutes. Serious damage to the eyes in 30 minutes. Death after 30-60 minutes.
- 700 - 1,000 ppm = Rapid unconsciousness, “knockdown” or immediate collapse within 1 to 2 breaths, breathing stops, death within minutes.
- Above 1,000 ppm = Nearly instant death.
There can also be long-term health effects. If you breathe in enough hydrogen sulfide that you lose consciousness, you may have lingering headaches, a poor attention span, and memory and motor function issues after waking up. OSHA says people have also had problems with their cardiovascular system after exposure.