NHS greenhouse emissions account for five per cent of the UK's total greenhouse gas production. Medicines have been identified as a major problem, with about a quarter of the NHS's carbon footprint coming mostly from drugs we use every day, such as painkillers, antibiotics and asthma inhalers. 

Used by more than 5 million people in Britain, asthma inhalers are a particular problem. Research data published in February this year shows that overuse of just one type of reliever medication in asthma is responsible for 250,000 tons of greenhouse gas emissions in the UK. Putting that into perspective, the study's lead author, Dr Alexander Wilkinson of East and North Hertfordshire NHS Trust told the British Thoracic Society that that's like driving an average diesel car for nearly 900 million miles. 

The problem lies in the vastly potent greenhouse gases hydrofluoroalkane, tetrafluoroethane and heptafluoropropane, used as propellants in the inhalers. 

The study also found that half of UK asthma patients overuse their short-acting beta2-agonist (Saba) inhalers. Britons use Saba inhalers about three times as much as people in other large European countries.  "Reliever overuse is a major contributor to greenhouse gas emissions in respiratory care", said Dr Wilkinson.

Elen Jones, director of the Royal Pharmaceutical Society in Wales, leads the society's carbon-footprint reduction initiative. He says we should switch to other products. "Metered dose inhalers represent three per cent of NHS greenhouse gas emissions" he says, and points to propellant -free powdered inhalers, which have a carbon footprint up to 37 times smaller than gas-pressurised inhalers. "We need to switch patients to devices that have the least damaging propellants."