To the roll call of greenhouse gases that are warming our planet, gases like carbon dioxide and methane, you can add some others, European researchers say, courtesy of your local hospital and the anesthetic gases used in its operating rooms.
Levels of surgical anesthetic gases including isoflurane, desflurane and sevoflurane in the atmosphere have increased over the last 10 years and have been measured as far away from their sources as the air over Antarctica, the scientists say.
Although the overall amounts may be low compared with the more common greenhouse gases, there is concern because such medical anesthetic gases are much more potent when it comes to their potential of creating a greenhouse effect, the researchers point out in their study published in Geophysical Research Letters.
In terms of greenhouse warming potential, 2.2 pounds (1 kilogram) of one of the anesthetic gases, desflurane, is the equivalent of 5,512 pounds (2,500 kilograms) of carbon dioxide, explains study leader Martin Vollmer, an atmospheric chemist at the Swiss Federal Laboratories for Materials Science and Technology in Switzerland.
"On a kilogram-per-kilogram basis, it's so much more potent," he says.
The gas nitrous oxide, even more common in the atmosphere and also used as an anesthetic, was not included in the study, the researchers said, because it also comes from many other sources having nothing to do with medicine.
When it comes to pollution sources, hospitals might not be the first thing that comes to mind, but in fact the new findings should not come as a surprise, says anesthesiologist Jodi Sherman at the Yale University School of Medicine.
"Health care in and of itself in the U.S. is one of the worst polluting industries," she notes. "It generates 8 percent of U.S. greenhouse gases according to one study."
Given that the World Health Organization has identified climate change as the health issue of most concern for the 21st century, "it behooves us to do a better job with emissions," she says.
The study findings were based on a determination of global concentrations of the anesthetic gases collected globally in the Northern Hemisphere since 2000, the researchers explained.
The most recent measurements from 2014 found the concentration of desflurane in the atmosphere was 0.30 parts per trillion (ppt), while isoflurane, sevoflurane and another anesthetics, halothane, registered at 0.097 ppt, 0.13 ppt and 0.0092 ppt, respectively.
That's a minuscule fraction of CO2 concentrations - measured at 400 parts per million in that same year - but the extreme greenhouse potential of the anesthetic gases makes them deserving of concern, the researchers say.
