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Doctors have never been ones to downplay the impact of climate change on health. As far back as 2009 the Lancet Commission on managing the health effects of climate change described it as the “greatest global health threat of the 21st century.” Last month, an international health organization representing more than 46 million health professionals wrote an open letter to COP28 president Sultan Al Jaber asking him to commit to a phase-out of fossil fuels in order to improve the health prospects of future generations and save lives. But some of the most impactful work doctors are doing to reduce global warming is happening in a surprising place: their own operating rooms.

The health care system is an unexpectedly large source of emissions, representing an estimated 8.5% of the United States’ carbon footprint. Emissions come from a variety of sources, from energy use and transportation, through to waste disposal. Within health care systems, operating rooms stand out as a major hotspot, generating 70% of hospitals’ waste and up to six times as much carbon as the rest of the health system.

“When you look at operating rooms and surgical waste, the anesthetic component contributes around 50-60% of all emissions” says Dr. Mehul Raval, professor of surgery at the Ann & Robert H. Lurie Children’s Hospital, Chicago, who has authored studies on how operating rooms can reduce their environmental footprint. “The other big area is disposable items and then the energy used in operating rooms.”

Only a small percentage of anesthetic gasses are actually metabolized by patients—the majority is exhaled as waste gas and vented directly to outside air releasing it back into the atmosphere. The worst offender is the gas desflurane, one of the most commonly used inhalation anesthetics. It has a global warming potential 2,500 times greater than carbon dioxide, and persists in the atmosphere for 14 years.

Dr. Kenneth Barker, a Scottish anaesthesiologist has led the charge to eliminate desflurane from all of Scotland’s hospitals. He remembers first hearing about the climate impact of desflurane in 2017, when he chanced upon a talk by Dr. Ted Pierce, an anesthesiologist and environmental advisor to the president of the Royal College of Anaesthetists. Pierce had been researching the environmental impacts of various commonly used anesthetic gasses for years, going as far as to create a calculator that compared the carbon emissions and costs of inhalational anesthesia.

Read more: Tackling Climate Change Can Save Hospitals Money

The differences between desflurane and other common alternatives, like sevoflurane, were too stark to ignore, says Barker. Desflurane’s global warming potential is 26 times higher than sevoflurane. The difference between using one bottle of desflurane for anesthesia to one bottle of sevoflurane is the carbon equivalent of driving a passenger car 2,200 miles versus 122 miles.

When Barker returned to his hospital, he started spreading the word, eventually creating an informal group of physicians in 2019 called “Green Anesthesia Scotland,” aimed at reducing the climate impact of inhaled anesthesia. It quickly became a nationwide group, and has morphed into what is today the National Green Theatres programme, supported by the Scottish government, and part of a country-wide initiative to reduce the carbon footprint of Scotland’s national health service. This March, NHS Scotland announced it had removed desflurane from its supply chain, becoming the first country in the world to eliminate the use of that anesthetic.

Ending the use of desflurane was made easier by the fact that Scotland has a national procurement system, and that there was a readily available substitute.

“Switching to sevoflurane was a low-hanging fruit,” says Barker. “Anesthetic gasses play an important role but there are other areas with a potentially much bigger impact,” he says. Direct emissions from hospital services and machines, and those related to energy use, only account for around 30% of its emissions, while the majority come from the health care system’s supply chain including the production of materials and machines used in the hospital as well as food and pharmaceuticals. Still, the ease of phasing out desflurane has inspired a growing group of clinicians to look more closely at other parts of the health care system.

Now, the National Green Theatres Programme will focus on additional environmental measures in medical settings, including eliminating single use instruments, improving waste disposal, and working with suppliers to improve the sustainability of their supply chains.

Scotland’s initiative to eliminate desflurane has inspired similar commitments globally. England aims to phase out the gas by 2024, and the European Union has formulated a proposal to ban the use of desflurane by 2026. In the U.S., a growing list of hospitals from Michigan to Seattle to Pennsylvania have either eliminated or committed to eliminating the gas with positive results both for the environment and their bottom line. As far back as 2013, the roughly 2,500-bed Yale New Haven Health System formally replaced the gas in favor of sevoflurane, with estimated savings of around $1.2 million that year across the health system.

“Desflurane is hundreds of times worse than the other alternatives, and it’s more expensive,” says Dr. Seema Gandhi, the medical director of sustainability at the University of California, San Francisco Medical Center (UCSF). Historical data suggest that because desflurane is eliminated faster from the body, patients wake up faster from anesthesia after surgery. However with changing anesthesia protocols, there is little clinical evidence to show that these benefits are relevant today. “There are no commiserate benefits of using desflurane, eliminating it is absolutely a win-win,” says Gandhi.

Gandhi spearheaded the fight to get desflurane out of operating rooms in the UCSF Medical Center, succeeding in 2019 saving the hospital $300,000 in a year and taking the equivalent of 159 cars off the road between 2018 and 2020. She’s now turned her attention to nitrous oxide, another volatile gas that is around 270 times more potent than CO2. Nitrous oxide is traditionally delivered via pipes, and most of the gas leaks in the process of delivery before it reaches the patient, so the main efforts involve shifting to small portable cylinders. The newest hospital was built entirely without a piped system for nitrous oxide, setting a trend she hopes other health systems in the country will follow.

Much of the efforts to eliminate desflurane in the U.S. have been done by small groups of dedicated practitioners, but Gandhi sees potential for it to go national. In 2022, the Agency for Healthcare Research and Quality, part of the U.S. Department of Health and Human Services, released a primer to help health care organizations reduce greenhouse gas emissions and protect communities from climate threats, including reducing the use of desflurane. Also last year, the American Society of Anesthesiologists released guidance on avoiding desflurane and nitrous oxide as anesthetics. This year it released guidance on using a low-flow system for delivering anesthetic gasses that would reduce overall emissions.

Part of the current effort now is to create more awareness among her peers and people in health care systems, with the hope to get as many systems as possible to take advantage of this quick fix, including getting California to ban desflurane. “It’s bad for the triple bottom line—economics, environment, and society as a whole,” she says. “There’s no reason we should keep using it.”

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