The fact that your breath is detectable through bricks and mortar — you would think — might be a bad thing, perhaps remedied by a breath mint or a trip to the bathroom to brush and floss. But actually, it's a good thing, especially if you ever find yourself trapped under the rubble of a collapsed building.
True, being trapped under rubble doesn't sound too pleasant, but you'll be happy to know that the chemicals in your breath will help get you rescued by acting as a sort of GPS locator.
Keen on this is a group of scientists from the UK, led by Loughborough University's Paul Thomas, who are developing an "electronic sniffer dog" that could help rescue disaster victims by detecting specific chemicals in their breath.
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Researchers say their device was able to detect the molecules of acetone and ammonia in the breath of participants in the study.
No, the scientists did not collapse a building on their subjects — they created a mock-up. Eight volunteers spent six hours "trapped" in a box, while their breath passed through a cylinder containing materials found in rubble such as concrete and glass. Thomas then recorded what molecules were detectable through the simulated rubble.
"We need to try and define in scientific terms what a 'signs of life detector' would need to respond to," Thomas told BBC News. "But what starts from a human and travels through a building may not be what gets to the end of the building– there's a whole range of materials that it has to pass over and through."
Besides ammonia and acetone, carbon dioxide and isoprene were also detected.
Thomas said that his team's signs of life detector "worked beautifully."
"Our chemical sensors detected what we were looking for rapidly, within an hour of someone being 'buried' there," he said.
The team now plans to do more testing with volunteers spending longer amounts of time "being buried," taking into consideration metabolite chemicals that could become apparent as victims go without food, as well as chemicals found in urine.