Carbon footprint evaluation for waste management of fluorinated anaesthetics in the UK using mathematical modelling

The UK NHS faces increasing pressure to diminish its carbon footprint, with fluorinated anaesthetic agents representing a significant source of direct greenhouse gas emissions. Several NHS trusts retain substantial quantities of unused stock and waste volatile anaesthetics, particularly desflurane, requiring appropriate disposal. However, a crucial unquantified aspect is the endpoint destruction routes and associated emissions for accumulated desflurane stock and waste anaesthetics. We developed a mathematical model accompanied by an open-source Python-based application programming interface to estimate equivalent carbon emissions and their climate impacts across disposal pathways. Stochastic modelling also estimates uncertainties of input parameters and their effects on model predictions. User-defined input parameters in the application programming interface allow practitioners to model specific destruction pathways. We identified high-temperature incineration in clinical waste streams as the most likely route, which, compared with release, shows reductions of more than 70% in equivalent emissions. Model predictions suggest that plasma destruction has the highest potential for reducing equivalent carbon emissions, to less than 5% from all waste fluorinated volatile anaesthetics by reducing the formation of products of incomplete combustion, with an associated reduction in climate impact. Crucial work still needs to be done to validate theoretical estimates, accurately assess the formation of products of incomplete combustion from fluorinated volatile anaesthetics under varying destruction conditions, and evaluate the feasibility of implementing the assessed waste streams.