Asthma patients are being encouraged to use more environmentally-friendly inhalers.
New guidance, which will be used to help those with the condition choose which device is right for them, includes details about the carbon footprint of each option.
It is hoped the information, published by the National Institute for Health and Care Excellence (Nice), will help patients select options which have less impact on the environment where possible.
It is the first time that Nice has published information on the carbon footprint of a medicine or device.
Many asthmatics currently use metered dose inhalers, which contain substances known as hydrofluorocarbons to help propel the dose into their respiratory system.
These devices have an estimated carbon footprint of 500g of carbon dioxide equivalent per dose.
Five doses from a metered dose inhaler can have the same carbon emissions as a nine-mile trip in a car, Nice said.
By comparison, dry powder inhalers contain just 20g of carbon dioxide per equivalent dose and work well for many patients.
Professor Gillian Leng, deputy chief executive of Nice, said: “People who need to use metered dose inhalers should absolutely continue to do so, but if you have the choice of a green option, do think about the environment.
“Cutting carbon emissions is good news for everyone, especially those with respiratory conditions.”
More than 26 million prescriptions for metered dose inhalers were written by GPs in England in 2016/17.
In 2011 they made up 70% of UK sales, compared to around 10% in Sweden, Nice said.
The new Nice decision aid also urges patients to return used inhalers to local pharmacies so that they can be safely disposed of, or to recycle them where the service is available.