Addressing Nitrous Oxide as a Greenhouse Gas, Part 1
Given its significant environmental impact, N2O will likely be phased out in health-care settings.
Earlier this year, I first came across the comment that nitrous oxide (N2O) was a greenhouse gas. The topic resurfaced again at the 2027 National Fire Protection Association’s (NFPA) 99 technical committee meeting in Kansas City, Missouri, where it became clear that N2O’s environmental impact would soon be a priority topic in health care. To understand the full scope, I started looking into the data and researching what alternative anesthetizing options may look like going forward.
Like many of you, I hadn’t considered nitrous oxide’s impact on climate change before, but my research revealed that agriculture is a major contributor to its emissions, while health care would be in the 3% range.
The surprising impact of nitrous oxide on climate
Since N2O is a greenhouse gas with significant warming potential, I began by looking into what the U.S. Environmental Protection Agency (EPA) and the American Society of Anesthesiologists (ASA) had to say about nitrous oxide and greenhouse gases.
“In 2022, nitrous oxide accounted for 6% of all U.S. greenhouse gas emissions from human activities,” notes the EPA in its “Overview of Greenhouse Gases,” (https://bit.ly/4gg4a1f). The agency attributes 75% of these emissions to agricultural soil management, with N2O released from fertilizers, manure and crop residues and increasing nitrogen levels in the soil.
Agriculture soil management, as identified by the EPA, was the largest source of N2O emissions in 2022, but other contributors include the combustion of certain fuels, the production of synthetic fertilizers, nylon manufacturing and the use of N2O in anesthesia and semiconductor industries (see Figure 1).
Once released, nitrous oxide molecules can persist in the atmosphere for an average of 121 years, making their impact on global warming long-lasting.
Given its significant environmental impact, N2O will likely be phased out in health-care settings. So, what alternatives are available, and what can we expect to see in the next five to 10 years?
Exploring alternatives to nitrous oxide
Several inhalation anesthetics are used for inducing and maintaining general anesthesia; below are only three:
1. Xenon. A noble gas, xenon (Xe-133) is a radiopharmaceutical used primarily in imaging procedures. It is colorless, odorless and possesses sedative and analgesic properties. Xenon is considered more potent than N2O, with 71% xenon able to anesthetize 50% of patients. Despite its advantages, xenon is not widely used due to the high costs associated with its production and recovery.
2. Sevoflurane (Ultane). Approved by the U.S. Food and Drug Administration for adults and children, sevoflurane is a halogenated anesthetic commonly used in inpatient and outpatient surgeries (https://bit.ly/3ZkQ9bR), Anesthesiology magazine notes. According to the ASA, patients emerge from sevoflurane anesthesia faster than from isoflurane, although recovery times are similar to those of propofol.
3. Desflurane. Another option for general anesthesia, desflurane has a faster onset and offset than other inhalational anesthetics but is associated with a higher greenhouse gas impact.
While xenon and sevoflurane present viable alternatives to nitrous oxide, they each come with their own challenges, such as cost or environmental impact (https://bit.ly/4g6tBlU). As health care continues to focus on patient outcomes and sustainability, transitioning away from N2O will require careful consideration of these factors.
Xenon, though promising, comes with cost and impact considerations that need further exploration. Additionally, some newer anesthesia machines already use refillable cartridges for anesthetics like sevoflurane, providing a more efficient and sustainable option. These cartridges also allow real-time monitoring, helping anesthesiologists fine-tune dosages and manage usage effectively.
Future considerations and NFPA 99’s role
The NFPA 99 guidelines are likely to play a role in regulating the waste gas disposal aspect of these gases. However, it remains to be seen how the NFPA will handle the new gases used on anesthesia carts and in the broader clinical setting. In the meantime, I am continuing my research and speaking with anesthesiologists to better understand the direction anesthesia is heading.
In Part 2, I’ll cover more insights on alternative gases, including any regulatory shifts and emerging technologies. This is an evolving issue, and I’ll continue reporting on new developments as they arise.
