Meet H2S: The Silent KILLER

Do You Work in the Permian or Eagle Ford Basin?

Sign up for PEC H2S Clear, and one of our PEC Training experts will help you find and register for the next available training class in your area.

Living up to its name as the “Silent Killer”, Hydrogen Sulfide (H2S) can instantly disable and kill within seconds. The recent tragedy of an Odessa worker and his wife killed by exposure to H2S really emphasizes that it’s not ONLY workers in danger. The importance of communicating the power of H2S and the danger posed to not only workers, but also the general public is essential.

Please download and share this H2S information poster outlining the warning signs of H2S and how to stay safe.

Download the H2S Information Poster

If you would like to obtain a larger, printed version of the poster, send us an email at

Where You Find H2S

H2S can occur naturally or be produced during industrial processes. Natural H2S is produced through the decomposition of organic material by bacteria within a low oxygen environment. During Industrial operations, H2S can form as a product, byproduct or waste material.

Oil & Gas Industry
Oil and natural gas wells; in refineries, where H2S is removed from natural gas and oil; and in pipelines and tankers used to carry unrefined petroleum.

  • Shale Shaker Areas
  • Fluid Treatment Areas
  • Rig Floor
  • Belle Nipple
  • Mud Tanks
  • Mud Pump Areas
  • Storage Tanks
  • Wellhead
  • Cellar
  • Drilling Floor
  • Pump House

Pulp and Paper Industry
H2S is a by-product of wood breaking down into pulp in making of paper, fertilizers, glues, dyes, plastic wrap, etc.

Construction Industry
Underground Utilities and Excavation work in swamps or landfills

Wastewater/Sewage Industry
Sewers, septic tanks, and sewage treatment plants

Agriculture Industry
Manure tanks, bogs, swamps and other places where organic material breaks down without oxygen

Other Industries include: Mining, Tunnels, Coke Ovens, Coal-fired Plants and Animal Processing Plants.

What to Do if Detected

Suit Up! – Put on your mask making sure the straps are snug and breath. Once yours is on, help anyone else around you.

Go Upwind! – If you don’t have proper breathing protection, then move upwind immediately. Always walk in the opposite direction of the way the wind is blowing. There should be an indicator in the area whether it is a windsock or a flag to show the wind direction.

Find People! – If you don’t see someone that was onsite with you, speak up and let others know. Unless you are properly trained and equipped, DO NOT go back to get them-You will not make it!

Get Help! – If all persons are accounted for, call the appropriate phone numbers provided by your company. If an emergency, call 911. Rescuers need to take caution when approaching victims who cannot evacuate independently, as to not be harmed themselves by H2S exposure. Respiratory protection is necessary when entering an H2S environment, and possibly a safety line, because of the very rapid toxic effects of the gas.

What are the Signs/Symptoms?

Reactions to H2S exposure can vary from person to person because everyone is different. Concentrations of H2S above 10 ppm (parts per million) are generally considered as unhealthy for continuous exposure.

Low Concentration
(0-10 ppm)
Moderate Concentration
(10-99 ppm)
High Concentration
(Over 100 ppm)

.01-1.5 ppm
Odor threshold (rotten egg smell is first noticeable to some.

3-5 ppm
Odor becomes more offensive. Prolonged exposure may cause nausea, tearing of the eyes, headaches or loss of sleep.

10 ppm
Fatigue, nausea and vomiting, headache, irritability, dizziness and difficulty breathing.

20 ppm
Irritated inflamed eyes and respiratory tract irritation after 1 hour.

50 ppm
Loss of smell after 15 minutes.

100 ppm
Loss of smell after 3 minutes. Gradual increase in severity of symptoms over several hours. Death may occur after 48 hours.

200 ppm
Sense of smell eliminated instantly. Burning eyes and nose. 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.

700-1000 ppm
Rapid unconsciousness, “kncokdown” or immediate collapse within 1 to 2 breaths, breathing stops, death within minutes.

1000-2000 ppm
Nearly instant death.

ppm = parts per million

How to Help a Victim and When to Seek Treatment

For an H2S victim to survive, you must react appropriately and quickly.

Inhalation Exposure:

  1. Move the victim to fresh air. If you are NOT trained to rescue an H2S victim, then do not attempt a rescue.
    Call 911 or EMS.
  2. If victim is not breathing and you have been trained to perform rescue breathing, give rescue breaths using a one-way valve.
  3. Be careful not to inhale the victim’s exhale breath as it may contain H2S.
  4. Keep the victim warm and at rest until help arrives.

Skin & Eye Exposure from Liquified H2S:

  1. Remove and isolate contaminated clothing and shoes.
  2. Flush with water for at least 20 minutes. (If frostbitten, use warm water; if burned, use cool water.)
  3. If still irritated, seek medical attention immediately.

Post Exposure or Long-Term Exposure:

  1. Seek medical attention.

How to Protect Yourself

  1. Understand and follow any policies and procedures required by the owner/operator and/or your company.
  2. Seek proper H2S classroom training that meets the industry accepted standard – ANSI/ASSE Z390.1-2017. PEC’s H2S Clear teaches students how to identify hydrogen sulfide and its sources, how to react when exposed, methods of detection, monitoring and protection, as well as rescue techniques, post-exposure evaluation and life support systems. This OSHA, API, and Texas Railroad Commission approved course meets and exceeds the standards outlined in ANSI/ASSE Z390.1-2017.
  3. If working in environments contaminated with H2S concentrations over 10 ppm, workers must wear air respiratory equipment, take annual training, as well as get a medical evaluation and respirator fit test.
  4. Always be aware of your surroundings and take heed of warning signs and alarms.

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