Decommissioning nitrous oxide manifold reduces carbon footprint and harmful emissions

Nitrous oxide is a potent greenhouse gas estimated to be nearly 300 times worse than carbon dioxide for the environment

Imperial College Healthcare NHS Trust has taken a step forward in its efforts to reduce greenhouse gas emissions by switching off the wall supply for nitrous oxide at Charing Cross Hospital and introducing a less-wasteful alternative supply.

Charing Cross is believed to be one of just a handful of major hospitals in England to decommission its entire nitrous oxide manifold – the system that delivers the gas to the pipelines around the hospital – in one go.

The move will reduce greenhouse gas emissions by at least 460 tonnes of C0₂e (carbon dioxide equivalent) a year, which is around 1% of the trust’s overall carbon footprint – the equivalent of driving a petrol car around the earth 57 times.

Environmental risk

Nitrous oxide has been used for over 175 years as part of anaesthesia within healthcare, but it is a potent greenhouse gas, estimated to be nearly 300 times worse than carbon dioxide for the environment.

And recent research highlighted how a significant proportion of nitrous oxide emissions at older NHS hospitals like Charing Cross is due to waste from manifolds and the associated old pipe structure.
The staff-led project is a big contribution to delivering on the trust’s Green Plan, specifically the goal of becoming more sustainable in the use of medicines, equipment, and anaesthetic gases, and is a result of many months of work to find a solution and test its feasibility.
While nitrous oxide is no longer available from wall-mounted sockets at Charing Cross, the team has made sure that an alternative supply is accessible for all clinicians who need it.

The original switch off took place in May and the manifold has now been decommissioned permanently, following a planned pause to make sure there were no issues.

A step forward

Dr Tom Dolphin, consultant anaesthetist at Imperial College Healthcare NHS Trust said: “This is a big step forward in our efforts to reduce the trust’s carbon footprint.

“It has been a real team effort over many months, with enthusiastic input from our pharmacy, sustainability, estates, and anaesthetics teams and I am delighted we’ve now made the switch permanent, following a pause to ensure there were no issues.

“We’re now aiming to do the same at other sites in the trust where nitrous oxide is used.”

Dr Bob Klaber, director of strategy, research and innovation at Imperial College Healthcare NHS Trust, added: “This is a really-innovative and impactful project and I am grateful to the many teams who worked so hard over the past six months to make it possible.

“We are one of the biggest NHS trusts in the country, with an ageing estate, and are absolutely committed to reducing our impact on the environment and reaching carbon net zero before 2045.”

The Trust also recently installed volatile capture technology (VCT) canisters designed to capture anaesthetic gases at Charing Cross, Hammersmith, and St Mary’s hospitals, in a large-scale feasibility trial funded by Imperial Health Charity to reduce carbon emissions in surgery.

Anaesthetic gases are potent greenhouse gases and when patients receive a general anaesthetic, the gases they exhale are normally released via pipes into the atmosphere from the hospital roof.

The new VCT canisters will capture significant volumes of the exhaled anaesthetic gases, which can then be purified and reused.

The team will use the findings from the feasibility trial to make a case to roll this out permanently across the trust.

Find out more about Imperial College Healthcare’s Green Plan.