Danny Johnson was on patrol outside Tampa, Florida, when a report came through of a possible shooting in a junkyard three blocks away. Arriving on the scene, he found an elderly man sitting on a tractor, with a large hole in his leg that was bleeding profusely.

Realising it would be some time before the ambulance arrived, Johnson opened a packet of sand-like material and poured it into the wound. Within seconds the bleeding had practically stopped, and the man survived. "The medic told me that had I not put the substance in there, the guy would probably have bled out and died," he says.

The material, called QuikClot, which is issued routinely to police officers in Hillsborough county, Florida, was developed for the US military to cut down the number of soldiers who bleed to death on the battlefield. More than 85 per cent of soldiers killed in action die within an hour of being wounded. Improved haemorrhage control "could probably save 20 per cent of the soldiers who are killed in action", says Hasan Alam, a trauma surgeon at Massachusetts General Hospital in Boston.

I've seen a lot of "science fiction" type technology this week. This item uses a sand like substance that can be poured into a wound and help blood clot. It's being used by some police and the Navy but the Army has yet to make it an official part of their equipment, though many soldiers still buy and carry it. The problem with the substance is that it generates heat as it absorbs moisture to seal the wound. Once they get that kink worked out it could become widely used, even in homes. A lot of lives could be saved.

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