Anaesthetic gases used to carry out smooth surgeries are accumulating in the Earth's atmosphere, where they are contributing to climate change, a new study has warned.
Over the past decade, concentrations of the anesthetics desflurane, isoflurane and sevoflurane have been rising globally, researchers said.
Like the well-known climate warmer carbon dioxide, anaesthesia gases allow the atmosphere to store more energy from the Sun. But unlike carbon dioxide, the medical gases are extra potent in their greenhouse-gas effects.
One kilogramme of desflurane, for instance, is equivalent to 2,500 kilogrammes of carbon dioxide in terms of the amount of greenhouse warming potential, said Martin Vollmer, an atmospheric chemist at the Swiss Federal Laboratories for Materials Science and Technology in Dubendorf, Switzerland.
"On a kilogramme-per-kilogramme basis, it's so much more potent" than carbon dioxide, said Vollmer, who led the study.
In a new scientific paper published in the journal Geophysical Research Letters, Vollmer and his colleagues report the 2014 atmospheric concentration of desflurane as 0.30 parts per trillion (ppt).
Isoflurane, sevoflurane and halothane came in at 0.097 ppt, 0.13 ppt and 0.0092 ppt, respectively. Carbon dioxide - which hit 400 parts per million in 2014 - is a billion times more abundant than the most prevalent of these anaesthetics.
The team did not include the common anaesthesia nitrous oxide in the study because it has many sources other than anaesthetics.
Researchers obtained their numbers by collecting samples of air from remote sites in the Northern Hemisphere since 2000, as well as aboard the icebreaker research vessel Araon during an expedition in the North Pacific in 2012 and at the South Korea Antarctic station King Sejong in the South Shetland Islands.
To turn these air samples into their global emissions estimates, the data were combined with a two-dimensional computer model of atmospheric transport and chemistry.
Although anaesthetics are small players in overall human-generated greenhouse emissions, they are a growing matter of concern to many in the health-care industry.
Anaesthesia gas abundances are growing and should not be overlooked, said Yale University School of Medicine anesthesiologist Jodi Sherman, a reviewer of the paper.
