From the Operating Room to the Atmosphere: The Climate Impact of Inhaled Anesthetics

BY JOSHUA CHEN

A 2022 study found that over 300 million people worldwide were administered anesthesia for surgery procedures every year¹. With life-saving surgical procedures on the rise and the ever-present desire to keep them as painless as possible, the number of patients administered anesthesia every year is also rising². While anesthetics can be administered intravenously, inhalation anesthetics are often touted as a strong alternative due to lower costs and ease of administering them³. Studies today generally find negligible differences between the two in terms of effectiveness. Inhalation anesthetics do, however, come with another cost. An environmental one. 

The healthcare sector contributes significantly to environmental pollution, primarily through greenhouse gas emissions and material waste. In 2022, the healthcare sector contributed to roughly 5.2 %⁴ of greenhouse gas emissions worldwide and roughly 8.5% of greenhouse gas emissions in the US⁵. Anesthetic gases, used for many modern surgical procedures, account for a substantial subset of these emissions and pose a considerable environmental threat due to their long-term effects. 

Greenhouse gases work by trapping heat in the atmosphere. By absorbing outgoing infrared thermal energy, they prevent heat from escaping into outer space, thus contributing to global warming. A study in 2022 found that inhaled anesthetics accounted for roughly 0.1% of the US’s total greenhouse gas emission effects⁶. Although a relatively small number, its long-term effects remain a pressing concern. Common anesthetic gases like desflurane, isoflurane, and sevoflurane have high global warming potentials (GWP), which measure heat-trapping capacity relative to CO₂ over 100 years. Desflurane has a GWP of 2,540, isoflurane 539, and nitrous oxide 273⁸.  Nitrous oxide, another commonly used anesthetic gas for dental procedures often referred to as “laughing gas” also has considerable environmental impacts⁹. The ozone layer absorbs harmful ultraviolet radiation from the sun, thus acting as Earth’s natural radiation shield. Nitrous oxide chemically reacts with ozone molecules, depleting the ozone layer and weakening the protection against the sun’s strong ultraviolet rays⁹.

Hospitals have been experimenting with change, phasing out desflurane due to its large GWP, as well as nitrous oxide due to its ozone-depleting properties⁷. Even after passing through a patient to anesthetize them, nearly 90% of the anesthesia gas remains chemically unchanged and therefore just as harmful to the environment. During and after a procedure, the exhaled gas from the patient remains potent, even if mixed with the other gases in the air.

Heavy exposure to anesthetic gases in clinical settings poses both occupational and potential long-term risks to clinical staff⁶. Short-term effects include dizziness, fatigue, and headaches¹⁰. Although not heavily studied, early studies in the 1970s suggested prolonged exposure to anesthetic gases over long periods of time may contain risks associated with genetic damage, liver disease, cancer, and congenital abnormalities, among others¹¹. Today there are exposure limits to prevent these things from happening¹⁰. At these lower concentrations, anesthetic gases show no evidence of adverse health effects.

To limit these risks and ensure that exposure levels remain low, hospitals have implemented gas scavenging systems to recollect the still-harmful gases¹². Active gas scavenging systems utilize fans and vacuums to create a pressure gradient that pushes the harmful gases into a collection unit. Passive gas scavenging systems rely on the gas to diffuse independently into the hospital’s ventilation system¹³. Most modern systems, however, are considered “open”, meaning that they are open to the atmosphere in order to prevent the build up of pressure. Collected gases are then funneled out of the operating room and eventually released into the atmosphere without further treatment¹³. While these systems protect patients and hospital staff, the environmental impacts of the gases remain unaddressed.

Capturing and reusing this gas to prevent environmental contamination poses a challenge. While high-quality ventilation systems in operating rooms are common, they are far fewer in post-operating rooms, where previously anesthetized patients still may exhale excess unchanged anesthetic gases⁶. Even so, ventilation systems that collect and then filter waste gases before releasing them into the atmosphere are almost completely nonexistent in actual clinical settings⁷. Carbon filters have been studied as potential methods of filtering waste gases¹⁴. Other companies have experimented with other adsorption techniques, causing the gas molecules to adhere onto a solid surface^15,16,17. Once captured, the gas can then be re-purified and recycled for use. Photocatalytic air purification has also been proposed as a way to break down these gases using sunlight, but the technology is still in its early stages¹⁸.

For now, recycling anesthetic gases seems more feasible than degrading them. Closed-circle breathing systems, which recycle exhaled air after filtration, have also been implemented to improve gas use efficiency without compromising patient safety by administering lower doses⁶. Although eliminating inhaled anesthetics isn’t practical for the time being due to its popularity among medical professionals, total intravenous anesthesia (TIVA) is a possible alternative¹⁹. Current studies find little to no variation on patient outcomes if TIVA is used instead of inhaled gas²⁰. Still, TIVA poses its own challenges, as it can be harder to administer ²¹. Another study conducted in 2024 studied how patients and practitioners reacted to the use of TIVA as a climate change mitigation strategy. Participants highlighted its operational challenges, monitoring requirements, and lower confidence with use, although greater training was recommended to address these concerns²¹.

The use of anesthetic gases is deeply embedded in modern medicine, but their environmental impact is becoming harder to overlook. While reducing emissions from these gases presents challenges, several viable strategies are available. Continued research, improved technology, and changes in clinical practice could make anesthesia more sustainable. As awareness grows, efforts to mitigate the impact of these gases may become an integral part of broader environmental initiatives in healthcare.

Joshua Chen is a sophomore in Saybrook College.

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References

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