Reduced oxygen environments (Hypoxic environments)

Normal air is a mixture of oxygen and nitrogen, together with small quantities of carbon dioxide and other gases. When the oxygen content is lower than normal air, e.g. when it is intentionally lowered for special applications, the resulting gas is called hypoxic air or low oxygen air.

Oxygen is critical for both life and combustion and the industrial applications of these environments include fire prevention systems which prevent ignition, particularly of papers and books in archives or libraries. They are also used to reduce oxidisation or oxidative degradation of fresh produce and other materials such as food, paintings, metals), for physical training and rehabilitation of athletes and in medical research.

Such systems require an enclosed area which is airtight; this and the specific risk of a reduced oxygen atmosphere created within this area, means these spaces meet the definition of a confined space and are subject to the Confined Spaces Regulations 1997.

Therefore, when a hypoxic air system is to be installed, or has already been installed, it has to undergo a suitably detailed risk assessment to meet the requirements of both these Regulations and the Management of Health and Safety at Work Regulations 1999, including consideration of the suitability of such a system for the specific application at its location, such as:

• Is the system necessary?
• Can the same effect be achieved by any other mechanism that does not risk damage to the health of those working in the area?
• Is there a requirement for staff to enter the area?
• Where will the vented gases be discharged; higher concentrates of oxygen can also be dangerous and vented gases may be higher in CO2 concentration.
• Safeguards to ensure the oxygen level remains at a safe level bearing in mind the staff working in the area; and
• Warning notices to advise of the existence of the confined space and, where oxygen levels are low enough to have a potential to cause injury, restrictions on entry e.g. key systems, authorised entry passes

The risk assessment should also consider any protective measures that may be required to ensure the health and safety of all persons having access to the protected space. The concentration of oxygen will decide the type of precautions you should take. Reduced oxygen levels have an impact on people working in the confined space and the lower the concentration the more likely that staff will be affected. You may need to:

• consider any pre-existing medical conditions employees may have and the impact working in reduced oxygen may have on those conditions
• initiate health monitoring of staff who will enter the confined space as part of their role.
• establish a system for identifying changes in health that may affect the employees ability to work in the confined space e.g. reduced oxygen can impact more dangerously on a pregnant woman and potentially the foetus.
• training in alarm recognition, evacuation processes and recognising the symptoms that oxygen depravation may cause
• provide relevant personal protective equipment which may include breathing apparatus
• assess the risks to employees from other issues such as the amount of exertion involved in the job which would increase respiration to provide more oxygen, temperature etc

Further information:

For more advice on your specific system speak to the manufacturer or supplier.

For more information on risk assessments read Controlling the risks in the workplace.

For more information on the Confined Space Regulations read Confined spaces: A brief guide to working safely or to understand the legal requirements of those Regulations see ACOP