Environmental accounting methodologies

Carbon accounting terminology can be a source of confusion. Terms such as ‘carbon footprint’, ‘ecological footprint’, ‘environmental footprint’ and ‘life cycle assessment (LCA)’ are commonly used interchangeably. In part, this inconsistency reflects a degree of dissensus, even among the scientific community, as to the underpinning methodological processes; the particular set of emissions that should be included in each assessment and the specific environmental impacts which should be assessed and communicated. In the healthcare context, the most commonly reported methods used to quantify environmental impacts are ‘carbon footprinting’ and ‘LCA’.

Carbon footprint

The concept of a carbon footprint and the general approach to its calculation have been recently described elsewhere in this journal.5 Internationally recognised standards for GHG accounting and reporting are produced by the GHG Protocol and cover a variety of contexts. The ‘Greenhouse Gas Accounting Sector Guidance for Pharmaceutical Products and Medical Devices’ (2012) was developed for the specific appraisal of pharmaceutical products and medical devices and builds on the widely used ‘Product Life Cycle Accounting and Reporting Standard’ 6 7 The task of footprinting a clinical pathway (as opposed to a single product) requires its own approach. In order to enable ‘more consistent quantification of the sustainability performance of care pathways globally, […] and to support decision-makers in their choices related to improving the performance of models of care’ the NHS’s Sustainable Development Unit published ‘Care Pathways: Guidance of Appraising Sustainability’ in 2015.8 This guideline can be used to appraise GHG emissions, water use and waste generation across a clinical pathway.

Life cycle assessment

LCA is a structured, comprehensive and internationally standardised method, which can be used to quantify the environmental impacts associated with products or processes over their entire lifecycle, from raw material extraction, production, to use and end of life. A key feature which distinguishes LCA from a carbon footprint is the ability to quantify a variety of environmental impacts beyond GHG, for example, water use, marine ecotoxicity or particulate matter. Conducting an LCA requires dedicated software and considerable time to complete while a key challenge for its application in healthcare is to obtain reliable and representative data. Data quality and availability depend on many factors, such as the scope, the system boundaries, the data sources, the data collection methods and the data validation procedures. Various software packages exist, but some involve costly licence agreements. A pair of international standards ‘ISO 14040 and 14044’ set out the principles, framework and requirements for an LCA.9 10 An LCA which solely quantifies GHG emissions is sometimes referred to as a ‘carbon footprint’.

However, the standards guiding the conduct of carbon footprinting and LCA are not fully prescriptive nor necessarily appropriate for the range of possible evaluations and comparisons of healthcare products, processes and care pathways. There remains room, within certain parameters, for methodological divergence, and the current literature demonstrates that a range of approaches have been deployed.11

Environmental accounting in gastroenterology

Within the specialty of gastroenterology, environmental scrutiny has been mostly directed at the practice of endoscopy. The volume of procedural waste has been a focus of concern and the subject of several published audits.12–15 Only recently have recognised environmental accounting methodologies been adopted to further explore the issue. Process-based LCA studies have been used to estimate environmental impacts related to the use of reusable and single-use duodenoscopes,16 17 endoscopic forceps, snares and haemoclips,18 the processing of gastrointestinal biopsies,19 and diagnostic imaging.20

However, the study boundaries of many of these process-based LCAs exclude important sources of emissions such as patient and staff travel, hospital building energy, pharmaceuticals, and the production, shipping and disposal of general supplies. The inclusion of these elements of the procedural pathway can give a more comprehensive and holistic analysis of the environmental impact of endoscopic practice, which is of particular use if comparisons are to be made with less-invasive or community-based diagnostics. Given the number of inputs involved in a complex process such as an endoscopic procedure, a carbon footprint can be more feasible to conduct than an LCA. This approach has been used to estimate endoscopy-generated GHG emissions at individual endoscopy units in France,21 Germany22 and Italy.23

Utility

There cannot be improvement without metrics to quantify the scale of a problem, and against which mitigation can be measured. That is the view conveyed within the quotation from Peter Drucker, and, in one form or another, probably the most commonly encountered argument for the value of environmental impact assessment. Highly relevant, also, is that national climate targets mandate that environmental impacts are measured, reported and explicit strategies published as to how impacts are to be mitigated.

Second, the complexity of the interaction between human activity and the natural world means that the most sustainable course of action in a given situation is not always intuitive. Intervention strategies, therefore, need to be informed by independent, objective assessment. Rigorous, validated environmental accounting is often considered a safeguard against misleading ‘green-washing’. The use of LCA, in particular, by virtue of its ability to provide estimates on a wide range of environmental impacts, helps protect against environmental ‘burden-shifting’, wherein a sole focus on GHG mitigation may neglect other important environmental impacts.

Organisations looking to improve their environmental performance want to know where resources and efforts should be best focused. Carbon footprinting and LCA can highlight the parts of a product or process which impart the greatest environmental impact; these ‘hotspots’ can then be prioritised and targeted in mitigation strategies. Environmental impact metrics also facilitate the benchmarking of services and products, potentially facilitating healthy competition and an iterative process of improvement against comparators, resulting in a positive cycle of decarbonisation. There is also the emotional argument; that metrics are necessary if the net-zero narrative is to sensitise an audience to the issue and act as a unifying and galvanising force. Carbon metrics translate invisible emissions into an understandable currency necessary to focus minds on the impact of the products we use and the services we provide.

Limitations

The application of carbon accounting in healthcare is a young and evolving discipline and there are limitations to these tools intrinsic to the modelling methods on which they depend.11 But the healthcare context, especially, demands that particular considerations are made when interpreting results and implementing interventions. There remains considerable heterogeneity in the methods deployed between studies, and so caution needs to be heeded when making comparisons between products and processes across studies.24

Measuring impact

Primary data can be difficult to obtain, and exact product manufacturing processes are often unknown to the research team. Manufacturers are wary of divulging proprietary information, and obtaining these data often require protracted negotiation and even confidential disclosure agreements. The assessment, therefore, requires that assumptions are made, and the result is inevitably a simplified representation of a process. Secondary data can be drawn from various life cycle databases which contain average data for a variety of products and processes. However, there is no uniformity across studies as to which databases are used. Furthermore, there is no standardisation as to the method used to convert this inventory data into environmental impacts (known as the ‘characterisation method’).

Interpretation

Those looking to optimise the environmental sustainability of a product or process may wish to draw on the findings of multiple environmental impact assessments to inform decision-making. When comparing studies, it is important to consider any variation in the scope; whether there is consistency across the unit of analysis (functional unit), the ‘boundaries’, and the life cycle stages examined. A choice has to be made as to the elements of a process that are included in the assessment (be that the use of a product or a clinical care pathway); for instance, whether emissions from sterilisation, or patient travel are included. The rationale for the study scope and boundary should be justified, but studies which explore a similar process, but which have used different boundaries, are inevitably going to reach different results.

Second, energy and resource inputs for a model may not be static; for instance, shipping arrangements for a product are liable to change over time, or the energy source used to heat a building may switch to a less carbon-intensive fuel. To some extent, the significance of this variation in the result can be addressed with the use of sensitivity analyses, but readers of studies should consider whether the results remain valid for the purposes of their use. The same principle pertains to the generalisability of environmental impact assessments, for instance, international variation in the carbon intensity of electricity generation can mean that an energy-intensive process may be carbon-intensive in one setting but not another. This variable could determine whether a particular process remains environmentally significant, or even change the overall directionality of a comparison, for example, single-use versus reusable products. It is also possible that there is national variation in the activity data used, for example, the energy requirements of equipment required for a particular task, for which a variety of brands and models may be in use.

An important additional benefit of LCA over carbon footprinting is the ability to estimate a diverse range of ‘midpoint’ environmental impacts. It is possible that the sustainability benefits of one product when compared with another may not be aligned across all impact categories (eg, the manufacture of product A generates fewer GHG emissions than product B, but contains highly toxic chemicals). However, there is no consensus as to how these various impacts should be necessarily prioritised. LCA allows the aggregation of midpoint impacts into three ‘endpoints’: damage to ecosystems, damage to human health and resource depletion, but this step does not eradicate all possible trade-offs the decision-maker may face. This is particularly a concern when LCA is used solely to quantify GHG emissions.

Implementation

There are both conceptual and pragmatic questions that arise from the use of findings from environmental impact studies in healthcare decision-making. Indeed, the question of how environmental impacts should be best incorporated into the healthcare commissioning process (to some extent similar to other scientific findings) is a point of active debate.25 Greener NHS has already declared that procurement decisions will be influenced by suppliers’ alignment with the NHS net-zero ambition: their roadmap states that by 2030 ‘suppliers will only be able to qualify for NHS contracts if they can demonstrate their progress through published progress reports and continued carbon emissions reporting’.26

The role of environmental impact data in influencing the design of care models and services is perhaps even more complex, and the UK’s National Institute of Clinical Excellence is examining how environmental sustainability considerations should be included in a new framework for prioritising topics across their recommendations.27 But this is not an easy task: the provision of safe healthcare services already requires that commissioners consider numerous variables, including clinical performance, cost, convenience factors and infrastructure constraints. This process takes time, and the adding of another variable carries risk that service reconfiguration could be influenced by sustainability profiles that do not hold over time.

Lastly, we should reflect on whether there are any conceptual impediments to the use of environmental impact data in the commissioning of healthcare services. If the aim of effective healthcare is to be understood as an attempt to prolong healthy life, then tensions can be seen to exist between the aims of healthcare and those of the decarbonisation agenda. These tensions become apparent if one were required to compare the environmental sustainability of care pathways in which the clinical outcomes were in any way divergent. An individual’s ‘carbon expenditure’ on healthcare is only a fraction of per capita annual carbon emissions,28 yet this ‘commodity’ (healthcare) also influences human survival. The existence of this dynamic has implications when modelling environmental impacts because strategies which aim to optimise patient outcomes while specifically reducing healthcare-related emissions could paradoxically increase net emissions (a form of burden-shifting) by virtue of the resulting extension of an individual’s period of healthy consumption. The alternative— to aim for a reduction in net emissions— could therefore result in an unintended consequence: the prioritising of less effective models of healthcare. This dilemma is perhaps most easily conceptualised when considering to what extent the prioritisation of ‘preventative healthcare’ is ultimately aligned with national economic decarbonisation.