When disasters strike, the clock starts ticking for people who are trapped or injured: Each second can mean more loss of life, so immediate search and rescue efforts are imperative. A new study headed up by researchers from the University of Technology Sydney suggests that creating an odor profile based on the decomposition of carcasses could give search and rescue workers a better chance of finding survivors with help from scent-detection dogs.

According to the U.S. Department of Health and Human Services, millions of people in America are impacted by unexpected tragedies and natural disasters each year. Even after a disaster has taken place, survivors still face a risk of death or physical injury in addition to the loss of their homes, possessions, and communities.The aftermath of a natural disaster can include an increased risk for heart attacks, stillbirths, and even “broken hearts.” It also includes the morbid job of finding and identifying victims at a disaster site.

Search and rescue teams deployed immediately following a natural disaster use detection dogs to find both survivors and human remains. However, deciding when to send out scent dogs is problematic. By establishing a scent profile of body decomposition, scent dogs could be trained to more easily recognize a change in the odor of a recently deceased person.

"Our motivation for this study came from information local law enforcement agencies gave us about using scent-detection dogs to help them find living and deceased victims after mass disasters like earthquakes," said lead researcher Prue Armstrong in a statement. "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."

Armstrong and her colleagues conducted their research using pig carcasses. Pigs are considered physiologically similar to humans. Three domestic pig carcasses were left on a soil surface during an Australian summer to decompose naturally. Smells coming from the carcass were collected several times a day over the course of 72 hours using new technology called comprehensive two-dimensional gas chromatography - time-of-flight mass spectrometry (GC×GC-TOFMS).

Researchers were able to identify a total of 105 volatile organic compounds (VOCs) that contribute to odor profiles during decomposition. The VOCs belonged to a variety of different chemical classes and the majority contained either nitrogen, sulfur, or ester compounds. Although the makeup of VOCs changed by the hour, the odor profile changed drastically at the 43-hour mark. At this point, the research team found that the odor changed from a “living” odor to a “deceased” odor.

"We were quite surprised to be able to identify so many volatile organic compounds during the early postmortem period," Armstrong added. "We believe this was possible because we used GC×GC-TOFMS to analyze our decomposition odor samples; previous studies using more simple chromatography techniques did not identify as many — or any — VOCs."

Following concerns over environmental conditions, the researchers conducted another trial using the same format during the Australian winter with the same results.

Source: Armstrong P, et al. Establishing the volatile profile of pig carcasses as analogues for human decomposition during the early postmortem period. Heliyon . 2016.