Using the most common type of inhaler to treat conditions such as asthma is as bad for the environment as eating meat, a new study suggests.

Research led by the University of Cambridge found that inhalers, particularly the metered-dose style, account for almost 4% of the greenhouse gas emissions of the NHS.

Metered-dose inhalers contain liquefied compressed hydrofluoroalkanes (HFA), a significant greenhouse gas.

Replacing just 10% of them with the cheapest equivalent dry-powder inhaler, which have a carbon footprint between 10 and 37 times lower, could save the NHS £8.2m a year and reduce carbon dioxide emissions by 58,000 tonnes a year. That is the same as 180,000 return car journeys from London to Edinburgh.

The researchers said that on an individual level, replacing each metered-dose inhaler with a dry powder equivalent would save between 150kg and 400kg a year.

That is similar to the amount of savings an environmentally conscious person could achieve by taking steps around the home such as recycling, installing wall insulation or cutting out meat, the study said.

Dr James Smith, from the University of Cambridge, said: "Our study shows that switching to inhalers which are better for the environment could help individuals, and the NHS as a whole, reduce their impact on the climate significantly.

"This is an important step towards creating a zero carbon healthcare system fit for the 21st century."

But Dr Alexander Wilkinson, consultant in respiratory medicine from East and North Hertfordshire NHS Trust, said it was important that patients did not stop using their usual treatments without consulting their doctor, just to reduce their carbon footprint.

Current advice is for patients to review conditions and treatments at least annually with healthcare professionals. That would provide an opportunity to discuss whether environmentally friendly inhalers are available and appropriate for them to use, the Cambridge team said.

People can also make sure they are using their inhalers correctly, return finished ones to pharmacies for proper disposal and avoid throwing away half-full items to help reduce the carbon footprint of their medication.