Anaesthetic gasses make up about 2% to 5% of the NHS's carbon footprint, and efforts are under way to tackle other medical gases like nitrous oxide.

Scotland has banned the use of the inhaled anaesthetic desflurane in its hospitals due to the threat it poses to the environment, becoming the first country to do so.

The United Kingdom's National Health Service (NHS) says the gas, used to keep people unconscious during surgery, has a global warming potential 2,500 times greater than carbon dioxide.

UK hospitals have already begun phasing out the anaesthetic. In the last few years, more than 40 hospital trusts in England and a number of hospitals in Wales have stopped using it.

NHS England plans to stop using desflurane completely by early 2024, except in exceptional circumstances.

It estimates that this will reduce harmful emissions by around 40,000 kilitonnes, equivalent to powering 11,000 homes every year, according to NHS analysis of desflurane use in 2020.

Other countries, including many in Europe, are likely to make similar moves in the next few years.

Banning the anaesthetic in Scotland, from its peak use in 2017, would cut emissions equal to powering 1,700 homes a year.

Kenneth Barker, an anaesthetist and clinical lead for Scotland's national green theatres programme, said he was shocked to find the anaesthetic drug he had used for more than a decade for many major and routine operations was so harmful to the environment.

"I realised in 2017 that the amount of desflurane we used in a typical day's work as an anaesthetist resulted in emissions equivalent to me driving 670 miles that day," he said. 

"I decided to stop using it straight away and many fellow anaesthetists have got on board.

"When you are faced with something as obvious as this and with the significance it has to the environment - I am very glad we have got to this stage."

Many hospitals have switched to safe and effective anaesthetic gases with less warming potential such as sevoflurane, which has a global warming potential 130 times that of carbon dioxide, or to using alternative non-gaseous anaesthetics and more efficient equipment.

Scottish Health and Social Care Secretary Humza Yousaf said: "Programmes like this are key to our transition to become a net-zero health service, whilst ensuring patient safety remains at the heart of every clinical decision."​​​​​