A colourless and odourless gas, oxygen is an important part of the atmosphere and is necessary to sustain life. However, if levels become too high, it can become highly dangerous.

This week, we take a look at the dangers of high AND low levels of this everyday essential gas.

What is oxygen?
Oxygen is the by-product of photosynthesis, the process by which plants and algae harness the power of sunlight to create cellular carbohydrates from water and carbon dioxide. Carl Wilhelm Scheele initially discovered oxygen in 1772. The word oxygen comes from Greek words: oxus (acid) and gennan (to generate)

The dangers of too much oxygen
Oxygen (O₂), normally present in air at 20.9%, is essential to human life. It is generally recognised that low O₂ levels are dangerous.

Possibly, less well understood is that too much oxygen in the air can also be highly dangerous if care is not taken. Increased levels can be caused by O₂ leaking into the general environment around processes which employ oxygen; from welding and flame cutting, to food preservation and packaging; across a wide range of industrial sectors, from steelworks to chemical plants; and across a variety of medical applications, from breathing equipment to hyperbaric chambers.

What are the hazards?
From the norm of 20.9% oxygen, an increase to just 24% significantly increases risk – not only do things ignite more easily, but they can burn hotter and more fiercely. Extinguishing a flame could become almost impossible. Under pressure, pure oxygen can react violently with materials such as oil and grease, which might usually be considered quite unreactive.

Many materials used routinely in other circumstances are incompatible with use in oxygen-rich environments, as they may spontaneously catch fire or react explosively.

Ways to prevent oxygen enrichment
Ideally, workplaces should be risk assessed and all reasonable, practicable precautions taken to ensure safety. A careful examination of the risks from using oxygen should be included in such an assessment. Other ways to prevent high levels of oxygen is to ensure equipment is kept in a good condition and to take care when using it. Ensure good ventilation is also established.

What should you do if you suspect oxygen enrichment?
– Turn off the oxygen supply
– Extinguish cigarettes and open flames
– Ensure the room is well ventilated
– Identify and repair the source

Oxygen use in the work place – Fire and Explosion Hazards is a useful guide for anyone working with oxygen cylinders. Published by the UK Health & Safety Executive (HSE), it highlights good standards, enabling companies around the world to conform to best practice. Download a free PDF from the UK government’s HSE website.