Minimizing sevoflurane use is crucial due to its significant greenhouse effect. CONTRAfluran™ captures exhaust anaesthetics, mitigating pollution and potentially enabling recycling with a 90% recovery rate. An unanswered question remains what proportion of the consumed sevoflurane is captured during mask anaesthesia and the resulting extent of pollution reduction. This study aims to quantify sevoflurane consumption and the efficiency of CONTRAfluran™ in reducing pollution during mask anaesthesia by different anaesthetists.