The smell of death that may help save the living

If you’ve ever caught whiff of festering roadkill, you’ll know death stinks.

Turns out, that stench consists of traceable odour molecules that change over time, as shown by an Australian study published in Heliyon. The finding may help rescue teams at mass disaster sites determine the best strategy to recover victims.

University of Technology Sydney scientists laid out three domestic pig carcasses at a field study site in Western Australia and let them decay naturally. (When it comes to body composition, fur-free, omnivorous pigs mimic humans better than other animals.)

Over each carcass they placed a steel hood which sucked air from around the body to a sampling tube. The team then analysed the scent profile every few hours for three days using a new, highly sensitive gas chromatography technique.

Comparing the air to that of a pig-free control site, the scientists identified 105 organic compounds that were specific to the air surrounding the decaying carcass. These compounds belonged to different chemical classes but nitrogen, sulfur and ester compounds were the most abundant.

Knowing when that scent shift happens may help guide victim rescue strategies.

The scientists found that after 43 hours of decomposition the scent profile shifted significantly, which the authors describe this as a change from a “living” to a “deceased” smell.

Knowing when that scent shift happens may help guide victim rescue strategies in mass disasters, such as earthquakes, tsunamis or terrorist attacks.

Despite being fitted out with high-tech camera and microphone equipment, a search and rescue crew’s most valuable assets are still detector dogs that can sniff out the bodies. They’re fast and can cover a large area.

But search dogs are often trained to detect either living or deceased victims, and knowing which dogs to deploy, and when, could be key to finding victims more quickly.

For now, the scent analysis is skewed to the conditions of the researchers’ study site, but the team is already broadening its odour experiments to different environments.

“We hope our findings give rescue teams the information they need about the optimal time frame in which to deploy human scent dogs versus human remains detection dogs to best ensure the recovery of victims following a mass disaster,” lead author Prue Armstrong said.