A study published in the Journal of Breath Research said that the molecules from the breath and sweat of humans could be used to detect their locations in crisis situations such as collapsed buildings due to earthquakes or bomb blasts.
The survivors could be located using sensors that would sniff out metabolites, the gassy by-products of breakdown mechanisms, which come from breathing, sweating and urinating. Paul Thomas, a professor at Loughborough University in central England said that this was the first scientific study on sensing systems that could detect trapped people.
Thomas said that a device could be used in the field without laboratory support. It could monitor signs of life for prolonged periods and be deployed in large numbers. In the past dogs have been trained to detect these compounds but they need frequent rest and expose the animal and the trainer to danger in search and rescue operations.
The sensors are being tested with human volunteers. Over five days, eight participants spent six hours at a time in a simulated collapsed building. The sensors rapidly detected human-generated carbon dioxide and ammonia in plumes of air that wafted through gaps in the rubble. The devices were able to pick up the acetone and isoprene cast off by the human bodies as well. There was a marked decrease in ammonia levels when the participants were asleep, but researchers could not explain why.