Sweat and breath could be used to find buried victims of earthquakes and terrorist attacks such as 9/11, a study has shown.
Scientists are working on a portable "sniffer" device that can locate signs of life under piles of rubble.
To help them, volunteers took part in a unique "trapped human" experiment.
Over five days, eight participants spent six hours at a time in a simulated collapsed building.
They lay in a coffin-like "void" while a variety of sensors probed plumes of air circulating through broken glass and reinforced concrete.
The sensors detected carbon dioxide, ammonia and organic compounds released from the volunteers' breath, sweat and skin.
Professor Paul Thomas, from Loughborough University, who co-led the study, said: "This is the first scientific study on sensing systems that could detect trapped people. The development of a portable detection device based on metabolites of breath, sweat and skin could hold several advantages over current techniques.
"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, as opposed to a handful of dogs working, at risk to themselves and their handlers, for 20 minutes before needing extensive rest."
The findings appear in the Journal of Breath Research, published by the Institute of Physics.
A spokesperson for the institute said: "As the first study of its kind, this preliminary work can be built upon to help prepare for future disasters such as those tragedies we've seen recently in Japan and New Zealand."