ObjectivesTo compare global warming potential (GWP) of hospitals converting from single-use sharps containers to reusable sharps containers (SSC, RSC). Does conversion to RSC result in GWP reduction?DesignUsing BS PAS 2050:2011 principles, a retrospective, before/after intervention quantitative model together with a purpose-designed, attributional ‘cradle-to-grave’ life-cycle tool, were used to determine the annual greenhouse gas (GHG) emissions of the two sharps containment systems. Functional unit was total fill line litres (FLL) of sharps containers needed to dispose of sharps for 1-year period in 40 trusts. Scopes 1, 2 and 3 emissions were included. Results were workload-normalised using National Health Service (NHS) national hospital patient-workload indicators. A sensitivity analysis examined areas of data variability.SettingAcute care hospital trusts in UK.Participants40 NHS hospital Trusts using RSC.InterventionConversion from SSC to RSC. SSC and RSC usage details in 17 base line trusts immediately prior to 2018 were applied to the RSC usage details of the 40 trusts using RSC in 2019.Primary outcome measureThe comparison of GWP calculated in carbon dioxide equivalents (CO2e) generated in the manufacture, transport, service and disposal of 12 months, hospital-wide usage of both containment systems in the 40 trusts.ResultsThe 40 trusts converting to RSC reduced their combined annual GWP by 3267.4 tonnes CO2e (−83.9%); eliminated incineration of 900.8 tonnes of plastic; eliminated disposal/recycling of 132.5 tonnes of cardboard and reduced container exchanges by 61.1%. GHG as kg CO2e/1000 FLL were 313.0 and 50.7 for SSC and RSC systems, respectively. A sensitivity analysis showed substantial GHG reductions within unit processes could be achieved, however, their impact on relevant final GWP comparison varied <5% from base comparison.ConclusionsAdopting RSC is an example of a sustainable purchasing decision that can assist trusts meet NHS GHG reduction targets and can reduce GWP permanently with minimal staff behavioural change.