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People with asthma are being encouraged to use "greener" inhalers by the NHS, if it is suitable for them.

Around 70% of inhalers used in the UK are the types that have high levels of greenhouse gases - compared to around 10% in Sweden

The National Institute for Health and Care Excellence says "environmentally-friendly" dry powder inhalers contain 25 times less pollutants.

The guidance says not everyone would be able to use them, but more could.

This is the first time NICE has addressed the carbon footprint of a medicine.

It is a reaction to the 10-year NHS plan published earlier this year, which recommended a greater emphasis on environmentally-friendly approaches in the health service.

Wide variation in carbon footprint of inhalers

Some inhalers - called metered dose inhalers - contain propellants known as hydrofluorocarbons to deliver the medicine quickly to the patient during an asthma attack.

These have an estimated carbon footprint of 500g carbon dioxide equivalent per dose.

It means five doses from one is the equivalent of a nine-mile trip in a typical car.

By comparison, dry powder inhalers have 20g carbon dioxide equivalent per dose, but are only recommended for people who have milder attacks.

More than 5 million people use inhalers across the UK.

Prof Gillian Leng, from NICE, said patients need to talk to health staff about what inhalers are best for them.

"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."

Dr Samantha Walker, of Asthma UK, said: "If anyone is thinking about changing their inhaler or needs advice, we recommend that they visit their GP or asthma nurse."