It goes without saying that oxygen is the only component of the air we breathe that is capable of supporting life. Air is composed of approximately 21% oxygen, 78% nitrogen and other trace gases.
Asphyxiation is the greatest hazard associated with nitrogen and other inert gases, such as argon and helium, leaking into a working environment and displacing the oxygen.
However, the addition of any gas, except oxygen, to air reduces the oxygen concentration through displacement and dilution. Breathing as little as one or two breaths of air containing too little oxygen can have serious and immediate effects, including unconsciousness.
Because there are no warning signs of reduced oxygen concentrations, these environments, usually confined spaces, are extremely dangerous.
The Effects of Oxygen Depletion on the Human Body
Human beings differ in their exposure to low oxygen concentrations. People may experience giddiness, mental confusion, loss of judgement, loss of coordination, weakness, nausea, fainting, loss of consciousness and death.
The immediate effects of low oxygen environments are due to the human body’s oxygen transport system. Blood absorbs oxygen from the air in our lungs to fuel the cells in our bodies. Our brain is the organ most sensitive to the lack of oxygen.
Within five seconds after inhaling only a few breaths of oxygen-free gas, there is a rapid drop in the oxygen concentration of the blood. Mental failure and coma follow a few seconds later.
Symptoms or warnings are generally absent, but even if they are present, the loss of mental competence, weakness, loss of coordination or loss of consciousness prevents victims from helping themselves or even summoning help. Death can occur in just two to four minutes.
Risk Assessments for Oxygen Depletion
All work areas where gases are stored, handled or used must be risk assessed. This is especially the case with respect to work in confined spaces.
The Health and Safety Executive define a confined space as any space of an enclosed nature where there is a risk of death or serious injury from hazardous substances or dangerous conditions, such as a lack of oxygen. Some confined spaces are fairly easy to identify, such as enclosures with limited openings. However, it is not possible to provide a comprehensive list of confined spaces, as some places may become confined spaces when work is carried out, or during their construction, fabrication or subsequent modification.
Under the Management of Health and Safety at Work Regulations, organisations must carry out a suitable and sufficient assessment of the risks for all work activities to decide what control measures are necessary for safety.
Confined Spaces Regulations and Safe Systems of Work
With respect to confined spaces, this means identifying the hazards present, assessing the risks and determining what precautions to take. It also means compliance with the Confined Spaces Regulations.
These regulations require operators to avoid entry into confined spaces where possible, for example by doing the work from outside. If entry into a confined space is unavoidable, then operators must follow a safe system of work and ensure that adequate emergency arrangements are in place before the work starts.
Oxygen Monitoring Systems
The safe system of work should include the use of oxygen monitoring systems. Human senses cannot detect an oxygen-deficient atmosphere, so the only way that operators can detect low oxygen concentrations is with real-time monitoring.
The use of oxygen monitors is strongly recommended in work areas where high concentrations of gas can accumulate. Oxygen monitors usually have two alarms. The first one sounds when the oxygen percentage in the air falls to 19.5% and the second, with a different sound, alarms when the oxygen concentration falls to below 18%.
Emergency Arrangements for Oxygen Depletion
With respect to emergency arrangements, operators must be aware that if they find a colleague who has collapsed as a result of entry into an oxygen-depleted atmosphere, they should call for help and definitely not enter the atmosphere, as if they do there will be two people collapsed.
Remember, you cannot hold your breath long enough to pull a victim out of the contaminated area.
Oxygen depletion is a real hazard where gases are handled and used in or near confined spaces.
Is Your Team Prepared?
Are your staff aware of the hazards posed by a lack of oxygen and the control measures necessary in order to work safely?
If not, and you require training on oxygen depletion hazards and safe working practices with compressed and cryogenic gases, please contact us on 01270 758890 or at admin@gassafeconsultants.co.uk.
