Some chemicals and work processes can deplete oxygen levels from the air and create an asphyxiation hazard for your workers. Asphyxiation hazards are particularly dangerous because in many instances there are no visible indicators; workers entering an oxygen deficient environment can quickly lose consciousness or die. This blog takes a closer look at asphyxiation and the three ways chemicals can impact oxygen levels in the breathing zones of your workers.
IMPORTANT: Our focus in this blog is to help you identify areas of your workplace that could present an asphyxiation hazard. Identifying hazards is only one step in your risk management plan, so we encourage you to download our free eBook How to manage the risk of Hazardous Chemicals in the workplace to learn how to also assess and control the asphyxiation hazards at your worksites.
What is an asphyxiation hazard?
The air we breathe everyday contains approximately 21% oxygen, 78% nitrogen , and 1% mix of other gases (argon, helium, carbon dioxide). If oxygen levels in our breathing zone fall below 21%, this now oxygen deficient environment creates an asphyxiation hazard.
As oxygen levels fall (between 11-18%) workers suffer physical and mental impairment, eg. it takes longer to perform a task, cognitive functions slow, and coordination is affected. With no sensory indicators (eg, a colourless, odourless and tasteless gas has displaced the oxygen in the room), workers may not even notice they have become impaired.
Once oxygen levels are below 11% workers are at high risk of losing consciousness and when oxygen percentages are below 8% (unconsciousness inevitable), the chances of resuscitation and recovery without permanent brain injury is minimal.
IMPORTANT: Lack of oxygen can bring on headaches and vertigo, in some cases the victim will have trouble speaking and communicating.
How chemicals create an oxygen deficient environment
To fully identify the asphyxiation hazards at your workplace, you’ll need to understand how the hazardous chemicals you use (in particular compressed gases) impact oxygen levels in work areas. Chemicals can deplete oxygen from the air in three ways:
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Gases displacing oxygen - all gases in high concentrations are asphyxiation hazards. When other gases (eg, argon, helium, CO2, LPG, etc) are released into the atmosphere, they displace the oxygen and reduce the amount of O2 available to sustain human life. This situation is often caused by compressed gases leaking from cylinders and holding tanks. Gases under pressure can quickly fill a confined space.
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Consumption of oxygen by a chemical process - simple things like rusting and corroding machinery, fuel burning, or rotting vegetation produce gas (eg, methane, carbon monoxide). These gases consume oxygen and create the hazard.
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Inhaling a chemical - some chemicals (if inhaled in strong enough concentrations) affect the body’s ability to absorb oxygen eg, cyanide can asphyxiate a worker by binding to the haemoglobin in the blood preventing them from breathing.
IMPORTANT: Working in an enclosed or confined space with inadequate ventilation, where hazardous vapours can accumulate, is a potential asphyxiation hazard. Safe Work Australia.
Where could asphyxiation hazards exist at your job site?
Now you have a better understanding of how chemicals can deplete oxygen from the air, consider now all the places where an asphyxiation hazard could exist. Here are some examples:
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Confined spaces - silos, mine tunnels, manholes, pipelines, storage tanks, bulk tanks on trucks, compartments and engine rooms on ships, vats, cold storage, underground vaults, rail cars, boilers, and cellars. Even a room with all the windows and doors closed can become a dangerous confined space if you are carrying out welding, spray painting, or cleaning with chemicals. Chemical stores without sufficient ventilation can also be a problem.
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Low lying areas - low lying areas like open pits and trenches, wells, open-topped water and degreaser tanks, and cellars are high risk for asphyxiation hazards. Gases that are denser than air (eg, LPG) can easily accumulate in these areas.
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High areas - roof spaces and lofts can also become hazardous when escaped gases that are lighter than air accumulate at the top.
Minimising asphyxiation risks
If you have asphyxiation hazards at your workplace you will need to conduct a full risk assessment. Control measures will focus on:
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Ventilation - if work areas and chemical stores lack sufficient natural ventilation you may need mechanical ventilation systems (blowers, fans etc) to maintain air quality.
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Preventing gas leaks - ensuring gas cylinders and other holding tanks are stored correctly (valves closed and upright) plus checked regularly for leaks, worn fittings, and damaged valves.
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Air quality testing - you may need safe operating procedures that include testing air quality before workers enter a confined space or other high risk area.
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Breathing apparatus - your workers may require self contained breathing apparatus.
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Hazard awareness and training - Make sure your staff understand asphyxiation hazards and use their breathing apparatus and PPE correctly.
REMEMBER: Workers have died or lost consciousness while welding work with compressed gases with inadequate ventilation.
Next Steps
If you have a list of potential asphyxiation hazards at your job site, we suggest downloading our free eBook How to manage the risk of Hazardous Chemicals in the workplace. We’ll walk you through the full risk assessment process and give your the tools and templates you need to assess and control these, and other chemical hazards. Download and read it today by clicking on the image below:
