Sustainability in anaesthesia and critical care: beyond carbon

Learning objectivesBy reading this article, you should be able to:•Outline the importance of the biosphere and its constituent parts.•Describe the impact of pollution and climate change on each other and on the overall planetary health.•Detail the impacts of healthcare-related activities on environmental pollution, from procurement to use to waste.•Adopt strategies to mitigate some of the effects of healthcare on the environment and on health.Key points•Earth's capacity to support life has reduced in recent decades, driven by pollution, habitat loss and climate change.•Medical equipment and drugs contribute to environmental harms through the extraction of raw materials, manufacturing, transport and disposal. This is exacerbated by excess waste, including disposable and single-use equipment.•Drugs and their metabolites (notably propofol and antibiotics) are commonly discharged into water by wastage or excretion. Their effects on aquatic life can be considered in terms of persistence, bioaccumulation and toxicity.•Efforts to mitigate the environmental impacts of healthcare should be holistic in their approach to risks and benefits; clinicians and policymakers should attempt to balance greenhouse gas emissions with other harmful effects.•Strategies to address the ecological impacts of healthcare include reducing consumption, avoiding disposable or single-use equipment, recycling and eliminating waste. Our planet is in the midst of an ecological crisis. This ecological crisis is most often discussed in terms of global warming, described by the Lancet Commission as ‘the biggest global health threat of the 21st century’. Healthcare services are now dealing with an increasing number of climate change-related pathologies, but as a major producer of greenhouse gases (GHGs) they are contributing to their own workload. Carbon dioxide equivalent (CO2e) is the measure used to account for emissions from all gases that contribute to global warming, including CO2, methane, nitrous oxide and others. Globally, it is estimated that healthcare accounts for 4% of overall carbon emissions; if healthcare were a country, it would have the fifth largest carbon emissions in the world.1McGain F. Muret J. Lawson C. Sherman J. Environmental sustainability in anaesthesia and critical care.Br J Anaesth. 2020; 125: 680-692Abstract Full Text Full Text PDF PubMed Scopus (66) Google Scholar There is therefore increasing scrutiny of healthcare-related carbon emissions. The NHS in England, for example, has recently committed to achieving carbon ‘net zero’ by 2040 and demonstrated a reduction in ‘carbon footprint’ of 580 kt CO2e in 2021. Around 5% of acute hospitals’ carbon emissions are from inhalational anaesthetic agents, and this has focused anaesthetists’ attention on their role in mitigating the carbon footprint of healthcare.2National Health ServiceDelivering a ‘Net Zero’ National Health Service. NHS England and NHS Improvement, London2020Google ScholarClinical scenarioMrs J is a 70-yr-old woman with hypertension and Type 2 diabetes mellitus, who is listed for an elective total knee replacement after consultation with an orthopaedic surgeon. Two weeks before surgery, she attends a preoperative clinic and has blood tests and an ECG. Two days before surgery, she attends hospital for SARS-CoV-2 screening. On the day of surgery, her husband drives her to hospital. She gets changed into a hospital gown, her observations are taken and an i.v. cannula is inserted. She is seen by her surgical and anaesthetic teams. Mrs J, who tries to lead a sustainable lifestyle, has noticed that her preoperative care has involved a lot of transport and has already generated a lot of waste. She is apprehensive that her operation may be similarly resource-intensive and asks the doctors about the medicines, equipment and energy involved in surgery (Fig. 1). She wants to know what the hospital is doing to make her care ‘greener’. Reducing the emission of GHGs is a key tenet of sustainable healthcare practice. However, focusing on carbon at the exclusion of other concerns, such as ecotoxicity, air quality and water pollution, is problematic (Fig. 2), not least because neglecting these factors may contribute to worsening climate change by damaging Earth's defences against global warming. In this article, we move ‘beyond carbon’ by describing the systems that comprise Earth's biosphere, outlining the broader environmental implications of anaesthesia practice on these systems and suggesting ways to mitigate negative impacts on planetary health. The biosphere is where life occurs on Earth. It comprises the lithosphere (land), atmosphere (air) and hydrosphere (water). The components of the biosphere are interconnected and mutually reliant. Oceans cover 70% of Earth's surface, contain 97% of Earth's water and 80% of all living organisms and produce 50% of Earth's oxygen. They act as a buffer to climate stressors, absorbing 90% of excess heat energy and 25% of carbon dioxide. Oceans store 40 trillion metric tonnes of carbon (16 times more than land and 50 times more than the atmosphere). However, as acidification increases, oceanic capacity to absorb further carbon decreases, thereby reducing buffering against global warming.3Dryden H. Duncan D. Climate regulating ocean plants and animals are being destroyed by toxic chemicals and plastics, accelerating our path towards ocean pH 7.95 in 25 years which will devastate humanity.2021https://ssrn.com/abstract=3860950Date accessed: January 23, 2022Google Scholar Global warming directly affects the health of oceans. Effects include marine heat waves and rising sea levels, which are projected to rise by at least 29 cm by 2100, resulting in a 100-fold increase in the risk of flooding.4Turley C. Racault M.-F. Roberts M. et al.Why the oceans matters in climate negotiations.2021https://www.gla.ac.uk/media/Media_795093_smxx.pdfDate accessed: January 23, 2022Google Scholar Oxygen solubility is reduced in warmer water, with more profound effects in the mid-water region (1,000–5,000 m depth), having an impact on many marine species. Deoxygenation also affects coastal waters, and its effects are amplified by land-derived nutrients causing eutrophication and the multiplication of Vibrio bacteria and harmful algal blooms.4Turley C. Racault M.-F. Roberts M. et al.Why the oceans matters in climate negotiations.2021https://www.gla.ac.uk/media/Media_795093_smxx.pdfDate accessed: January 23, 2022Google Scholar These effects are changing ocean currents, impacting on fish populations and migration. Aside from the ecological damage, this impact on fish stocks affects livelihoods and the food supply chain. Plankton thrive in acidic environments, yet their biomass has declined by 50% in the last 70 yrs, along with overall marine life.3Dryden H. Duncan D. Climate regulating ocean plants and animals are being destroyed by toxic chemicals and plastics, accelerating our path towards ocean pH 7.95 in 25 years which will devastate humanity.2021https://ssrn.com/abstract=3860950Date accessed: January 23, 2022Google Scholar This gap is thought to be because of toxic chemicals and microplastics, which affect phytoplankton and zooplankton, even in extremely low concentrations. Most of these chemicals originate on land, and over this same period of time the human population has tripled. The pH of oceans is currently around 8.1 and has decreased significantly over the last century. Now, large areas of oceans are devoid of life, and if ocean pH drops to 7.95, an estimated 80–90% of all marine life will be lost (Fig. 3).3Dryden H. Duncan D. Climate regulating ocean plants and animals are being destroyed by toxic chemicals and plastics, accelerating our path towards ocean pH 7.95 in 25 years which will devastate humanity.2021https://ssrn.com/abstract=3860950Date accessed: January 23, 2022Google Scholar The combined effect of climate change and pollution on the oceans is damaging the biological carbon pump that is driven by phytoplankton. The reduced ability of the oceans to mitigate against rising atmospheric CO2 results in further acidification and a dangerous positive feedback loop. Climate change efforts, therefore, need to be coupled with action to stop toxic chemicals from reaching the oceans and waterways, which is one of the five ‘tipping points for a healthy and productive ocean’ outlined by the United Nations Global Compact.5United Nations Global Compact5 Tipping points for a healthy and productive ocean by 2030.2019https://www.unglobalcompact.org/library/5726Date accessed: January 23, 2022Google Scholar If oceans ‘fail’, humanity will simply cease to exist. The decline in capacity of the biosphere to support life is also reflected on land, with studies showing 10% year-on-year decline in insect biomass. The main driver behind this decline is pollution.3Dryden H. Duncan D. Climate regulating ocean plants and animals are being destroyed by toxic chemicals and plastics, accelerating our path towards ocean pH 7.95 in 25 years which will devastate humanity.2021https://ssrn.com/abstract=3860950Date accessed: January 23, 2022Google Scholar Outdoor air pollution is the fifth commonest cause of mortality worldwide, accounting for 4.2 million deaths annually. Major pollutants include sulphur dioxide, nitrogen oxides, volatile organic compounds (VOCs) and particulates.6Schraufnagel D.E. Balmes J.R. Cowl C.T. et al.Air pollution and non-communicable diseases: a review by the Forum of International Respiratory Societies’ Environmental Committee, part 1: the damaging effects of air pollution.Chest. 2019; 155: 409-416Abstract Full Text Full Text PDF PubMed Scopus (238) Google Scholar Emissions can be from natural sources, such as volcanoes, but the majority are human-made, most significantly arising from fossil fuel combustion. Primary air pollutants are those pollutants released directly from the source, and secondary pollutants result from interaction between compounds in the atmosphere (e.g. ozone from nitrogen oxides and VOCs in the presence of sunlight). Air pollution is exacerbated by global warming, as higher temperatures accelerate the formation of some pollutants and increase dispersal.7Kinney P.L. Climate change, air quality, and human health.Am J Prev Med. 2008; 35: 459-467Abstract Full Text Full Text PDF PubMed Scopus (251) Google Scholar Deforestation is the second largest human-made source of GHG emissions after fossil fuel combustion. Although not as significant as the oceans, rainforests act as a global carbon sink. The Amazon rainforest alone is estimated to store up to 200 billion imperial tons of carbon but has seen 20% of its area deforested in the last 60 yrs, with another 20% at risk.8Nobre C.A. Sampaio G. Borma L.S. et al.The fate of the Amazon forests: land-use and climate change risks and the need of a novel sustainable development paradigm.Proc Natl Acad Sci U S A. 2016; 113: 10759-10768Crossref PubMed Scopus (372) Google Scholar The main causes of deforestation include forest clearance for agriculture, most notably for the production of soya beans (the main component of the i.v. formulation of propofol) and palm oil, and droughts and fires caused by climate change itself.9D’Amato G. Vitale C. Rosario N. et al.Climate change, allergy and asthma, and the role of tropical forests.World Allergy Organ J. 2017; 10: 11Abstract Full Text Full Text PDF PubMed Scopus (22) Google Scholar Shoreline erosions can force plant growth further back and expose tree roots, leading to tree fall. This increases the risk of flooding and causes the resuspension of sediments, which impacts aquatic plants and fish spawning; habitat destruction; and, ultimately, biodiversity loss. 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