Denver Health lost 90% of N₂O to leaks. So the gas was turned off.

Deep inside Denver Health's main building, on a locked floor that even most of the doctors who work at the hospital have never visited, is a cramped room filled with eight tall, blue compressed cylinders around giant oxygen tanks and beneath low-hanging pipes and pipes Gas.

The cylinders contain nitrous oxide – N₂O, the inhaled anesthetic known as nitrous oxide – and from this room, pipes throughout the hospital carry the gas to operating rooms and other places where it can be used. Or at least it did.

Last month, Denver Health switched from using nitrous oxide piped centrally from these always-open tanks to using smaller, portable tanks that are placed in operating rooms and can be turned off when not in use. Dr. Amanda Deis, a pediatric anesthesiologist at the hospital, was among those who helped close the buttons on the cylinders.

“It was a pretty monumental day,” she said.

The change has two reasons. First, nitrous oxide is a powerful greenhouse gas and destroys atmospheric ozone. And second, hospitals across the country waste a lot of it.

When Deis calculated how much nitrous oxide the hospital was purchasing and how much nitrous oxide the patients were using, she found that nearly 90% was lost to leaks throughout the hospital. This isn't a joke.

These leaks – every coupling and valve in the system provides an opportunity for gas to escape – are never enough to cause indoor air quality concerns. The hospital is testing to be sure.

However, the leaks mean that loose nitrous oxide is a significant factor in a hospital's overall climate footprint. And it's not just a problem at Denver Health – hospitals around the world have seen similar leak rates.

Dr. Jodi Sherman, a professor of anesthesiology at Yale School of Medicine and an expert on the effects of hospital climate, said the health care sector is responsible for nearly 9% of the nation's greenhouse gas emissions. Within a hospital, operating rooms are the most environmentally intensive areas, partly because of all the stuff that is used and thrown away, but also because of the climate impact of the anesthetic gas, she said.

Her research and the work of others has led to an increasing focus on improving the environmental sustainability of hospitals.

“We should all be working to make health care safer, and that includes curbing pollution,” Sherman said.

The majority of emissions attributable to the healthcare sector do not necessarily come from the vents and chimneys of hospitals themselves, but from the supply chain for all the things that hospitals use – the medical equipment, the personal protective equipment, the bandages, and so on. That's about 80% of the industry's emissions, Sherman said.

In contrast, research in the UK shows that inhalation anesthetics account for around 5% of a hospital's climate footprint. But these anesthetics contribute greatly to warming.

As a greenhouse gas, nitrous oxide is 300 times more potent than carbon dioxide. Another common anesthetic gas, desflurane, is 2,500 times more potent than carbon dioxide.

Hospitals have tried to address this problem in part by reducing the amount of nitrous oxide used. But Sherman said that wasn't enough.

“Even if you use less, the system is constantly leaking,” she said.

Hospitals cannot stop using nitrous oxide entirely because there are still areas where it is needed, Deis said. She mentioned pediatric surgeries – some children get sick if they are given an injectable anesthetic while they are awake. That's why Deis said she would give a child nitrous oxide to help him sleep before giving him other medications.

Therefore, the best option was to shut down the central tanks and switch to portable tanks. Late last month, the American Society of Anesthesiologists agreed, releasing a statement calling for the deactivation of centrally routed nitrous oxide systems in favor of portable tanks.

Dr. David Abts, an anesthesiologist at Denver Health, said the hospital was the first major facility in Colorado to switch to portable nitrous oxide tanks.

Combined with another change Denver Health has made – replacing desflurane with something more climate-friendly – ​​the switch is expected to reduce greenhouse gas emissions from Denver Health's operating rooms by over 95%.

“To put it in numbers,” he said, “that’s like taking over 1,800 SUVs off the road every year driving from Denver to New York City.”

These numbers mean Deis will breathe a little easier in the operating room.

“Knowing that I am already contributing to this greenhouse warming problem, it feels so good,” she said, “to know that we can make a system change to truly minimize our footprint while still keeping this drug available to patients close.”