Life Cycle Assessment of Medical Oxygen

Abstract

Medical oxygen is a vital healthcare resource provided to a patient to achieve their minimum required oxygen blood saturation. There is a growing interest in medical oxygen due to supply shortages experienced during COVID-19. There is limited sustainability research on medical products, their production and consumption, and their environmental impact. The World Health Organization has emphasized the need for environmental sustainability efforts and the resilience of health systems. This project considered a cradle-to-gate life cycle assessment (LCA) of medical oxygen. Medical oxygen, which accounts for a small fraction of total refined oxygen production, is produced using two technologies: (1) cryogenic distillation, where liquid oxygen is produced via liquefaction of air and then is transported to the site, (2) and pressure swing adsorption (PSA), where gaseous oxygen is produced, typically on-site, by passing ambient air through a molecular sieve. Four product systems for the LCA were considered. Product system 1, the baseline system, is a typical North American scenario: production via cryogenic distillation. Bulk liquid oxygen is transported to a hospital and then gasified for delivery via a pipe to the patient's bedside. In product system 2, oxygen is produced similarly to system 1, except liquid oxygen is transported and gasified at a regional facility. Oxygen gas is filled into cylinders, which are transported to the hospital. In product system 3, oxygen is produced at a hospital site via a PSA plant, which is then piped into the building. In product system 4, oxygen is produced and delivered immediately via a personal oxygen concentrator unit (which utilizes PSA technology) to a patient's bedside. Data were collected from the ecoinvent 3.8 database, industrial gas and medical experts, and publicly available information on company websites. OpenLCA software for running the system models and the TRACI life cycle impact assessment method were used. The reference period was 2021/2022, and the default location was Toronto, Canada, which has a relatively clean, low-carbon electricity grid. LCA results for the baseline system showed a global warming potential indicator value of 1.70x10-4 kg CO2eq/litre of gaseous oxygen, with electricity as the key driver. Results for system 2 were more than double, at 4.11 x10-4 kg CO2eq/litre, with cylinder-related activities such as transportation adding to environmental burdens in the supply chain. In comparison, for system 3, the PSA plant, yielded 8.44x10-5 kg CO2eq. Results for scenario 4, the personal concentrator, was incrementally higher, given its lower energy efficiency (1.23x10-4 kg CO2eq). A scenario analysis considering oxygen production in various locations of the world was also conducted. Overall, medical oxygen, when delivered efficiently to a hospital, has a relatively small environmental burden. However, the use of this critical resource is often wasteful. The results of the LCA can be useful to healthcare organizations, policy decision-makers and medical gas suppliers to improve sustainability practices of medical products and resource supply chains. The results also highlight aspects of the medical supply chain where there is a risk of disruption and where attention to health system resilience is needed.