The gases used to knock out surgery patients are accumulating in the Earth’s atmosphere, where they make a small contribution to climate change, report scientists who have detected the compounds as far afield as Antarctica. Over the past decade, concentrations of the anesthetics desflurane, isoflurane and sevoflurane have been rising globally, the new study finds.
Like the well-known climate warmer carbon dioxide, anesthesia 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 kilogram (2.2 pounds) of desflurane, for instance, is equivalent to 2,500 kilograms (5,512 pounds) of carbon dioxide in terms of the amount of greenhouse warming potential, explained Martin Vollmer, an atmospheric chemist at the Swiss Federal Laboratories for Materials Science and Technology in Dubendorf, Switzerland, who led the new study. “On a kilogram-per-kilogram basis, it’s so much more potent” than carbon dioxide, he said.
In a new scientific paper, 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 anesthetics. The team did not include the common anesthesia nitrous oxide in the study because it has many sources other than anesthetics. The team’s anesthesia-gas findings have been published online in Geophysical Research Letters, a journal of the American Geophysical Union.
The 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.