The Carbon Footprint of Hospital Services and Care Pathways: A State-of-the-Science Review

Abstract

Background: Climate change is the 21st century's biggest global health threat, endangering health care systems worldwide. Health care systems, and hospital care in particular, are also major contributors to greenhouse gas emissions.

Objectives: This study used a systematic search and screening process to review the carbon footprint of hospital services and care pathways, exploring key contributing factors and outlining the rationale for chosen services and care pathways in the studies.

Methods: This state-of-the-science review searched the MEDLINE (Ovid), Embase (Ovid), CINAHL (EBSCOhost), GreenFILE (EBSCOhost), Web of Science, Scopus, and the HealthcareLCA databases for literature published between 1 January 2000 and 1 January 2024. Gray literature was considered up to 1 January 2024. Inclusion criteria comprised original research reporting on the carbon footprint of hospital services or care pathways. Quality of evidence was assessed according to the guidelines for critical review of product life cycle assessment (LCA). PROSPERO registration number: CRD42023398527.

Results: Of 5,415 records, 76 studies were included, encompassing 151 hospital services and care pathways across multiple medical specialties. Reported carbon footprints varied widely, from $0.01\mathrm{kg}$ carbon dioxide (${\mathrm{CO}}_2$) equivalents (${\text{kgCO}}_{2}e$) for an hour of intravenously administered anesthesia to 10,200 ${\text{kgCO}}_{2}e$ for a year of hemodialysis treatment. Travel, facilities, and consumables were key contributors to carbon footprints, whereas waste disposal had a smaller contribution. Relative importance of carbon hotspots differed per service, pathway, medical specialty, and setting. Studies employed diverse methodologies, including different LCA techniques, functional units, and system boundaries. A quarter of the studies lacked sufficient quality.

Discussion: Hospital services and care pathways have a large climate impact. Quantifying the carbon footprint and identifying hotspots enables targeted and prioritized mitigation efforts. Even for similar services, the carbon footprint varies considerably between settings, underscoring the necessity of localized studies. The emerging field of health care sustainability research faces substantial methodological heterogeneity, compromising the validity and reproducibility of study results. This review informs future carbon footprint studies by highlighting understudied areas in hospital care and providing guidance for selecting specific services and pathways. https://doi.org/10.1289/EHP14754.

Figure 1.

PRISMA Flow diagram. Note: CINAHL, Cumulative Index to Nursing and Allied Health Literature; PRISMA, Preferred Reporting Items for Systematic reviews and Meta-Analyses.

Figure 2.

(A–F) Share of hospital services and care pathways that included specific contributors of the carbon footprint, presented for six different medical specialties. Medical specialties were graphically depicted if $>9$ individual services or pathways were studied among all sources identified. Data used for these graphs can be found in Table 4. The end of each black line indicates 100% of services/pathways represented in the figure. This figure should be interpreted with caution, given that it reflects only services/pathways that have currently been studied within these specialties and is likely not fully representative of these medical specialties as a whole. An empty area does not indicate that contributors had zero impact but only shows that it was not included for evaluation in the services/pathways studied within these specialties (i.e., missing data). Given that the chart represents individual services/pathways and not studies themselves, this figure also risks overvaluing those studies that included multiple services/pathways.