Air is composed of approximately 78% nitrogen, 21% oxygen and the other 1% being a mixture of argon, hydrogen, carbon dioxide and other rare gases. Obviously it is the oxygen component that is vital for human life. Medical professionals keep special types of oxygen masks to hand in case of emergency situations where patients need to breathe more easily. The types of oxygen masks available fall into two categories: rebreather and non-rebreather masks. Here we will give you a guide to both.

Rebreather oxygen masks have a soft plastic reservoir bag at one end which saves approximately one third of a person's air. The rest of the air is let out via ports in the side which are covered with a one-way valve. The purpose of this is to allow the person to 're-breathe' some of the carbon dioxide. This acts as a way of stimulating breathing again.

The non-rebreather masks are slightly different to the rebreather masks in that it has several one way valves fixed in the side ports. This particular type of oxygen mask will also have a reservoir bag attached, however the bad has a one way valve which will prevent the exhaled carbon dioxide from getting back into the resevoir. Clearly this mask will prevent the patient from re-breathing the air as it is able to escape through the side ports.

The purpose of both of these masks is to provide large high volumes of oxygen to patients who require them in emergency situations. Common conditions which require a high supply level of oxygen are cardiac disease, shock or trauma, severe blood loss, seizures and of course hypoxia (severe blood loss).

As well as rebreather and non-rebreather oxygen masks, there are several other types of masks - each with it's own specific use. Valve bag masks consist of a manual respirator who's purpose is to deliver pure oxygen to the patient, aeroplanes have oxygen masks which drop down from cabins in emergency situations, vets have specially made masks for use on animals, firefighters have their own self-contained breathing apparatus which also doubles up in it's use as it also provides eye and face protection. Because breathing oxygen is clearly hazardous in areas where fires may be burning, self contained breathing apparatus such as those used by firefighters are normally filled with compressed breathing air rather than oxygen. Mountain climbers also have their own specially made oxygen masks and of course fighter pilots have their own aviator masks.

Special caution must be exercised when it comes to using oxygen masks as oxygen is a obviously a flammable gas. In the case where someone is receiving oxygen there should be a 'no smoking' sign clearly displayed. Any electrical equipment in the vicinity should also be fitted with grounding adaptors to avoid the risk of any sparks. Any person using oxygen at home should be thoroughly trained and briefed on the dangers involved such as using the oxygen supply close to stoves or any portable heating units such as an electrical fire. Oxygen tanks music be held in a specially made cart so that they can be transported around without getting jolted, bumped or dropped as this could cause the tank to become punctured and risk the chance of an explosion.