SSS 2010-12-06（在线收听）

When they wheel you into the operating room, climate change is probably the last thing on your mind. But maybe it should be on your anesthesiologist's mind. Because the gases used to knock you out contribute to global warming.

Researchers, including one from the Jet Propulsion Laboratory at CalTech, a chemist from the University of Copenhagen and an anesthesiologist from the University of Michigan Medical School, studied three anesthetic gases: isoflurane, desflurane and sevoflurane.

The compounds are in a class of gases related to a refrigerant that's about to be banned in Europe. In the worst case, each pound of desflurane that enters the atmosphere is the equivalent of 1,620 pounds of carbon dioxide. The researchers say that on average the amount of anesthesia used worldwide for surgery annually has the warming equivalent of one million cars. The study is in the British Journal of Anaesthesia.

The other two gases have significantly less impact: isoflurane is only a third as powerful a greenhouse gas as is desflurane and sevoflurance has only an eighth of desflurane's effect. So, say the researchers, if a choice can be safely made, anesthesiologists should go with the one that's kindest to the climate.

Thanks for the minute. For Scientific American's 60-Second Science, I'm Cynthia Graber.