Anesthetics may make that tooth surgery bearable, but they are also contributing—at least somewhat—to climate change, a new study reveals. The gases act in much the same way as carbon dioxide (CO2), trapping energy from the sun in the atmosphere and warming the planet. Over the past decade, atmospheric concentrations of the commonly used anesthetics desflurane, isoflurane, and sevoflurane have risen globally to 0.30 parts per trillion (ppt), 0.097 ppt, and 0.13 ppt, respectively, scientists report in Geophysical Research Letters. Although those numbers may not seem like much—especially compared with CO2, which reached concentrations of 400 parts per million in 2014—the higher global warming potential of the anesthetics has some scientists worried. For example, every 1 kilogram of desflurane is equal to 2500 kilograms of CO2. They also tracked concentrations of another anesthetic, halothane—which many countries have phased out because it can damage the liver—and found its concentration had declined since 2000. Although nitrous oxide is also widely used as an anesthetic, the researchers purposefully did not include it in the study because, unlike the other gases, it is used in a variety of settings other than anesthetics, such as the food industry and in semiconductor manufacturing. Although no one is suggesting a return to the days of biting on a piece of leather or wood to distract from the pain of surgery, scientists argue that limiting or even eliminating the use of desflurane, the most potent of the three gases studied, would help. Also, the study’s researchers point out, no mandate exists that requires used anesthetic be captured and disposed of, and as a result, almost all of it is released directly into the atmosphere.