Asphyxiant ​​Gases

Primary reference(s)

OSHA Hazard Communication Standard (29 CFR 1910.1200)

CCOHS, 2024. How to work safely with - Hazardous Products Classified as “Simple Asphyxiants”. Accessed 14 July 2024

Annotations

Key relevant UN convention / multilateral treaty

1910.101 - Compressed gases (general requirements). Standard Number: 1910.101

Drivers

Asphyxiant gases can be released into the environment through various natural and human activities. In addition to deliberate or accidental release from cylinders or tanks of compressed gases, some examples of drivers or sources of asphyxiant gases are:  

• Industrial Processes: Many industrial processes involve the use or production of gases that can act as simple asphyxiants. For example:(a) Welding and metal fabrication can release argon or nitrogen used as shielding gases. (b) Chemical manufacturing processes may produce or release nitrogen, argon, or carbon dioxide. (c) Refineries and petrochemical plants can release methane and other gases during extraction, processing, and storage of hydrocarbons.
• Agricultural Activities: Agricultural practices can generate asphyxiant gases, particularly in confined spaces such as silos and manure pits. Decomposition processes in silage and manure can produce significant amounts of carbon dioxide and methane, which can displace oxygen.
• Mining Operations: Mining activities, particularly in underground mines, can generate asphyxiant gases due to natural processes and the use of machinery. Methane, carbon dioxide, and nitrogen can be present in mine atmospheres, posing risks to workers if not properly controlled.
• Confined Spaces: Any enclosed or poorly ventilated space has the potential to accumulate asphyxiant gases. This includes: Tanks, vessels, and storage containers where inert gases like nitrogen or argon may be used or present; underground tunnels, sewers, and manholes where natural gas or other gases may accumulate; Cargo holds of ships, where gases released from cargo or fuel may displace oxygen.
• Natural Sources: Some natural processes can also release asphyxiant gases into the environment: Volcanic eruptions can release large quantities of carbon dioxide, sulfur dioxide, and other gases; Decomposition of organic matter in stagnant water bodies, such as swamps or ponds, can produce methane and carbon dioxide; Geological processes, such as the release of gases from underground reservoirs or faults, can contribute to local concentrations of asphyxiant gases.
• Accidental Releases: Accidents involving storage, transportation, or handling of gases can lead to sudden releases of asphyxiant gases. For example, leaks from pipelines, storage tanks, or industrial equipment can result in the rapid buildup of gases in the surrounding area. 

Impacts

The diverse range of activities and processes that can contribute to the presence of asphyxiant gases in the environment, emphasizing the importance of proper monitoring, ventilation, and safety measures to prevent asphyxiation incidents. The impact of exposure to asphyxiant gases can range from mild symptoms of oxygen deprivation to severe injury or death, depending on the concentration of the gas, the duration of exposure, and individual susceptibility. Common outcomes of exposure to high concentrations of asphyxiant gases include:  

• Mild Symptoms: Inhaling low to moderate levels of asphyxiant gases may initially cause mild symptoms such as dizziness, headache, confusion, shortness of breath, and rapid heart rate. These symptoms can escalate with prolonged exposure or higher concentrations of the gas.
• Loss of Consciousness: Continued exposure to high concentrations of asphyxiant gases can lead to loss of consciousness and unconsciousness due to oxygen deprivation. This can occur relatively quickly in poorly ventilated spaces or confined areas where the gas accumulates.
• Suffocation and Asphyxiation: Without intervention, prolonged exposure to high concentrations of asphyxiant gases can result in suffocation and asphyxiation, leading to permanent brain damage or death.
• Explosions and Fires: Some asphyxiant gases, such as methane, have flammable properties. In environments where oxygen levels are depleted due to the presence of the gas, there is an increased risk of explosions or fires if an ignition source is introduced. 

Multi-hazard context

The figure below summarises common interactions between asphyxiant gases and other hazards. This information should be used with caution and not be solely relied upon in Disaster Risk Management, particularly as some interactions may not have been included. Note that hazardous events occurring together or locally in space or time may not necessarily cause, amplify or be otherwise related to each other. Specific examples of multi-hazard context can be found in the ‘Hazard drivers’ and ‘Impacts’ sections above.

Multi-hazard diagram

Risk Management

Risk Management strategies for dealing with asphyxiant gases aim to prevent exposure and mitigate the potential consequences. Here are some key risk management measures: 

• Hazard Assessment: Identify sources of asphyxiant gases in the workplace through thorough hazard assessments and risk evaluations. Determine the potential for exposure and assess the risks to workers and the surrounding environment.
• Engineering Controls: Implement engineering controls to minimize the release and accumulation of asphyxiant gases. This may include proper ventilation systems, gas detection monitors, and inerting or purging procedures in confined spaces.
• Administrative Controls: Develop and implement administrative controls, such as safe work practices, procedures, and training programs, to minimize the risk of exposure to asphyxiant gases. Ensure that workers are aware of the hazards and know how to respond in case of an emergency.
• Personal Protective Equipment (PPE): Provide appropriate personal protective equipment, such as respiratory protection, for workers who may be exposed to asphyxiant gases. Ensure that PPE is properly fitted, maintained, and used according to manufacturer guidelines and regulatory requirements.
• Emergency Response Planning: Develop comprehensive emergency response plans and procedures for dealing with accidental releases of asphyxiant gases. Conduct regular drills and training exercises to ensure that workers are prepared to respond effectively in case of an emergency.
• Monitoring and Testing: Implement routine monitoring and testing programs to assess the concentration of asphyxiant gases in the workplace and ensure that exposure levels remain below regulatory limits. Use gas detection equipment to continuously monitor air quality in areas where asphyxiant gases may be present. 

By implementing these risk management strategies, employers can effectively mitigate the hazards associated with exposure to asphyxiant gases and protect the health and safety of workers in the workplace. 

Monitoring

The section and the table below offer an overview of monitoring asphyxiant gases. This information can be used for forecasting within a national early warning system (EWS). Since EWS capacities and processes differ across countries, the most current and specific information regarding EWS should be obtained from the appropriate national or regional agency/authority responsible for disaster management.