NHS staff are being encouraged to drive to work less and bring in reusable cups and bottles to help the health service tackle climate change.
The suggestions are part of an NHS plan to cut carbon emissions to net zero and reduce air pollution.
Hospitals will also be told to switch to less-polluting anaesthetic gases and reduce emissions from buildings.
The plan follows the launch of Climate Assembly UK this week, which is looking at how the UK can best get to net zero.
The government has committed to the UK reaching the target – where the same volume of greenhouse gases is being emitted as is being absorbed through offsetting techniques like forestry – by 2050.