An ambulance often carries a huge range of first aid medical equipment when dealing with emergencies, but one of the most unusual, unique and remarkably important of these is the emergency blanket.

Also known as a “space blanket” due to its NASA origins, an emergency blanket is an astonishingly thin and light insulating material that is wind resistant, waterproof and reflects heat radiated by a person.

It is primarily used to fight the effects of heat loss and hypothermia and works with three main mechanisms:

• It is airtight, so air cannot rise and escape the way it can through breathable materials.

• Heat loss through sweating is reduced, making it particularly important for distance runners and other endurance athletes.

• It stops radiation by reflecting heat back into the body.

It is primarily used following exposure to extremely cold environments. Whilst this includes mountainsides and winter blizzards, it also helps to save people who have fallen into rivers, lakes or other sources of cold water by slowing the impact of hypodermic shock.

It has also been used as a makeshift shelter during emergency situations, as a reflective signal to call for help, or as an additional sheet to protect from cold ground if alternative shelters are unavailable.

There are some considerations to make when using them, especially in situations beyond an immediate emergency where more effective means to warm a body back up are otherwise unavailable.

Whilst they keep people warm, they are not traditional forms of insulation, and whilst they reflect 90 per cent of your body heat back to you, they will eventually not be enough to keep you warm if you are wet or trapped in extreme cold conditions.

They can also cause condensation due to a lack of breathability. This can lead to sweat, which can lead to heat loss over a long time.

Finally, they work best when used only a few times. Whilst they can be reused, they should be folded carefully.

Regardless, their low cost, high effectiveness, low weight and small profile have made them a vital piece of emergency equipment, one that has saved lives throughout the world.