Common Causes of Injury in the Oil and Gas Industry – Asphyxiation

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Asphyxiation (lack of O2 to the body) accounts for a surprising number of fatalities at well sites. Well gases, vapors, and volatile compounds (such as hydrogen sulfide (H2S), sulfur dioxide (SO2), carbon dioxide (CO2), carbon monoxide (CO), volatile organic compounds (VOCs), etc.) can come from the well or other sources (e.g., combustion engines).  Except for methane, these well gases, vapors, and volatile compounds are heavier than air and therefore settle in low spots around the well. Methane, on the other hand, rises and must be considered when working above open tanks and hatches. The accumulation of gases, vapors, and volatile compounds in confined areas can lead to asphyxiation, which can result in unconsciousness even if the lack of O2 lasts only for a few seconds, followed by death if O2 is not restored quickly.

Possible Solutions:

  • Perform an atmospheric assessment of the well site and select the proper monitor(s) for the conditions assessed. Air monitors that measure O2 concentration (such as multi-gas meters) are essential for protecting against asphyxiation. For more information about monitor use and capability, see the Multi-Gas Monitors Hazard Alert.
  • Train workers to stay out of confined spaces such as tanks, cellars, pits, and so forth, where vapors and gases can replace air. Make sure to comply with the requirements of 29 CFR 1910.146, Permit-Required Confined Spaces, before and during confined space entries.  Do not enter a confined space if not in compliance, or if acceptable entry conditions do not exist.

Be aware of serious health concerns at thief hatches and manholes on tanks and tankers. Workers who open hatches or manholes can be asphyxiated or can become unconscious from toxic hydrocarbon vapors escaping the hatch or manhole. Those working for extended times on tanks with open hatches or manholes can also be harmed. When performing these activities, wear air-supplied respirators. For more information, see the Tank Hazard Infographic and the National Institute for Occupational Safety and Health, NIOSH-OSHA Hazard Alert titled “Health and Safety Risks for Workers Involved in Manual Tank Gauging and Sampling at Oil and Gas Extraction Sites.”


KEMI does not assume liability for the content of information contained herein. Safety and health remain your responsibility. This information is to be used for informational purposes only and not intended to be exhaustive or a substitute for proper training, supervision or manufacturers’ instructions/recommendations. KEMI, by publication of this information, does not assume liability for damage or injury arising from reliance upon it. Compliance with this information is not a guarantee or warranty that you will be in conformity with any laws or regulations nor does it ensure the absolute safety of any person, place or object, including, but not limited to, you, your occupation, employees, customers or place of business.