Opinion Paper

Modelling the greenhouse gas impact of volatile anaesthetic agents in South Africa

Esther Cloete, Steffen Rex, Alain Kalmar

Received: 08 Dec. 2025; Accepted: 13 Feb. 2026; Published: 13 Apr. 2026

Copyright: © 2026. The Authors. Licensee: AOSIS.
This work is licensed under the Creative Commons Attribution 4.0 International (CC BY 4.0) license (https://creativecommons.org/licenses/by/4.0/).

Abstract

Desflurane has been removed from practice across the National Health Service (NHS) hospitals in the United Kingdom (2024)¹ and the European Parliament has prohibited the use of desflurane from 2026, with restricted exceptions. Given desflurane’s disproportionate greenhouse gas impact (GGI), we should consider whether South Africa should phase out the use of desflurane.

Keywords: CO₂-equivalent emissions; desflurane; global warming potential; greenhouse gas impact; sevoflurane; volatile anaesthetic agents.

Desflurane, a halogenated agent, has the highest GGI of all current volatile anaesthetic agents owing to its lower potency, higher radiative efficiency and longer atmospheric lifetime compared to sevoflurane. On a 100-year global warming potential (GWP100) basis, the impact is approximately 40–50 times higher than that of sevoflurane. Replacing desflurane with sevoflurane could therefore substantially reduce the GGI associated with volatile anaesthesia and contribute to a global reduction of 73% of the impact of halogenated anaesthetic agents.¹

Talbot et al. published a sales-based database of volatile agents that estimated greenhouse gas emissions for every country (2023)¹ South Africa was among six middle-income countries worldwide that showed a significant increase in desflurane sales.

Between 2014 and 2023, the GGI from desflurane increased by 151% in upper-middle-income countries and by 2 281% in low-income and low-middle-income countries. In contrast, high-income countries have reported a 52% decrease during the same period. These trends suggest that targeted efforts to reduce desflurane use in middle-income settings could materially lower global emissions attributable to volatile agents.

Based on the hospital and retail dataset for South Africa,¹ the estimated annual emissions attributable to volatile agents were 27 040 tonnes CO₂-equivalents (CO₂e) for desflurane, 5080 tonnes for sevoflurane, and 980 tonnes for isoflurane. These values respectively represent 81.7%, 15.3% and 3.0% of the total volatile anaesthetic emissions when using GWP100 as the standard comparator. Despite comprising only 9.2% of volatile maintenance anaesthesia time, desflurane accounted for 81.7% of emissions (Figure 1). Replacing desflurane entirely with sevoflurane would reduce South Africa’s total volatile emissions from 33 106 tonne CO₂e to 6661 tonne CO₂e. This replacement would eliminate the desflurane emissions (currently 81.7% of total volatile anaesthetic emissions) while shifting those procedures’ contribution to just 1.8% of the current total (i.e. the emissions from equivalent sevoflurane use in those cases), yielding an ~ 80% national reduction overall (Figure 1).

FIGURE 1: Share of maintenance anaesthesia time and associated CO2e emissions by volatile agent in South Africa.

Marin et al.² recently emphasised that, while GWP has limitations when comparing short- and long-lived greenhouse gases, our analysis compares two short-lived agents. In this context, sevoflurane is consistently preferable to desflurane across all climate-relevant parameters, including radiative forcing and atmospheric lifetime.

We also acknowledge that sevoflurane is almost completely degraded to trifluoroacetic acid (TFA), a persistent perfluoroalkyl and polyfluoroalkyl substance (PFAS), whereas desflurane has a molar TFA yield of only about 20%.^3,4 However, because approximately three times more desflurane is required to deliver 1 Minimum Alveolar Concentration (MAC) compared to that of sevoflurane, a typical desflurane anaesthetic still produces around 60% of the TFA generated during a comparable sevoflurane procedure. While somewhat lower, this difference does not constitute a strong argument in favour of desflurane and certainly does not compensate for its far greater greenhouse effect.⁵ Eliminating desflurane, therefore, still represents the most impactful and immediately actionable intervention, while the ultimate step to entirely avoid volatile-derived PFAS pollution is transitioning to Total Intravenous Anesthesia (TIVA).

Vorster et al.⁶ conducted an analytical cross-sectional study assessing sustainability practices among South African anaesthetists. For maintenance of anaesthesia, 73.5% preferred volatile anaesthesia without N₂O, with 79.9% opting for sevoflurane as the first-choice agent. Isoflurane and desflurane were generally the second-choice agents. Most respondents acknowledged climate change as a pressing concern and were willing to adopt environmentally sustainable practices into their daily clinical routines. Given its disproportionately high global warming potential, the continued use of desflurane was identified as a significant deviation from international sustainability guidelines.

Notably, although many anaesthesiologists indicate they would personally prefer TIVA⁷ for themselves or their close relatives, the majority of patients still receive volatile-based anaesthesia. This discrepancy underscores an ethical obligation to align routine practice with the standards physicians would choose for their own care, reinforcing the imperative for broader adoption of TIVA.

A small number of dissenting commentaries have argued that commonly used climate metrics, particularly GWP, are inappropriate for evaluating the impact of short-lived anaesthetic gases.^2,8 While the limitations of any single metric are well recognised, this critique remains highly debatable and does not alter the central conclusion of the present analysis. Irrespective of whether cumulative warming is assessed over a 20-year, 100-year or 500-year time horizon, desflurane consistently exhibits a disproportionately large heating effect, corresponding to approximately 7020 times, 2590 times and 741 times the cumulative atmospheric heat uptake of carbon dioxide, respectively.⁹

Even when adopting an exceptionally long time horizon of 500 years, the cumulative heat absorption associated with a single hour of anaesthesia using a modest 30 mL (≈ 44 g) of desflurane corresponds to what approximately 32.6 kg of CO₂ absorbs in this time window. This amount of heat uptake exceeds the combined emissions from all other anaesthesia-related sources – including electricity use for ventilation, monitoring and anaesthesia workstations – reported in most life-cycle assessments of peri-operative care.¹⁰ However, almost all of this energy is front-loaded as a single heat pulse delivered within the first decades after emission; when evaluated over a 20-year horizon, the same exposure corresponds to approximately 308 kg of CO₂, underscoring the disproportionate and immediate climate impact of desflurane use.

It has further been suggested that because most of desflurane’s radiative forcing occurs within the first decades after emission, its climate relevance becomes negligible on longer timescales. This interpretation is physically incorrect. The energy trapped during this period is irreversibly absorbed by the Earth system, contributing to long-term ocean heat storage, with associated reductions in oceanic CO₂ uptake capacity, cryosphere loss and the activation of additional climate feedback processes.¹¹ The fact that this warming is front-loaded in time amplifies – rather than diminishes – its climatic significance, particularly in the context of near-term climate thresholds and the activation of multiple positive climate feedback mechanisms.¹² Conflating atmospheric persistence with climatic impact is inconsistent with the established physical understanding of Earth’s energy balance.¹³

Limitations

Estimates depend on the accuracy and completeness of sales data, agent-specific CO₂e factors (including the selected GWP time horizon), case-mix and assumptions regarding fresh gas flows. Differences between public and private sectors, machine capability for low-flow anaesthesia, and patterns of nitrous oxide use are potential confounders.

Halothane emissions (5 tonnes CO₂e) were excluded in our calculations due to the negligible contribution.

Conclusion

An anaesthetist who routinely uses desflurane for a single year will have a greater impact on global warming in that year than a colleague who uses sevoflurane throughout their entire career.¹⁴ Twenty-five years of clinical research have failed to show that desflurane’s minor pharmacokinetic benefits lead to improved morbidity or mortality outcomes.^15,16 Therefore, phasing out desflurane in favour of sevoflurane and low-flow techniques could deliver substantial emission reduction, without compromising patient safety.¹⁷

Acknowledgements

The authors declare that they have no financial or personal relationships that may have inappropriately influenced them in writing this article.

Esther Cloete: Conceptualisation, writing – original draft and writing – review & editing. Steffen Rex: Conceptualisation, and writing – review & editing. Alain Kalmar: Conceptualisation, data curation, formal analysis, software, validation, visualisation, writing – review & editing. All authors reviewed the article, contributed to the discussion of results, approved the final version for submission and publication, and take responsibility for the integrity of its findings.

This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

Data sharing is not applicable to this article as no new data were created or analysed in this study.

The views and opinions expressed in this article are those of the authors and are the product of professional research. They do not necessarily reflect the official policy or position of any affiliated institution, funder, agency or that of the publisher. The authors are responsible for this article’s results, findings and content.

References