We have read with interest the increasing number of publications that seek, in line with the NHS long-term plan, to reduce the "carbon footprint" of the NHS. We think that the UK ETS does, however, create an objective basis on which to assess the most appropriate methods for CO SB 2 sb e emission reduction in anaesthesia. With current UK ETS carbon prices, for technologies costing more than £83 per tonne of CO SB 2 sb e saved, it would be cheaper and more economically efficient for the UK state, or NHS, to purchase emission permits, than buy the more expensive emission reduction technologies. [Extracted from the article]