Poorly controlled asthma is contributing to more than 300,000 tons of greenhouse gas emissions in the UK every year, an analysis has suggested.

Most of the carbon footprint comes from over-reliance on reliever inhalers, a study published in Thorax and carried out by Astra Zeneca found.

Using health records of 236,506 people with asthma between 2008 and 2019, the team found patients whose asthma is poorly controlled have eight times excess greenhouse gas emissions – mostly due to inhaler use – compared with those whose condition is well controlled.

The excess emissions – measured as carbon dioxide equivalent (CO2e) – are around the same as those produced by 124,000 homes, the study estimated.

Researchers categorised patients as either well controlled because they had no episodes of severe worsening symptoms and two or fewer prescriptions of short-acting beta-agonists (SABA) or poorly controlled if they were prescribed three or more SABA canister prescriptions or had one or more records of severe worsening symptoms.

It also took into account severe exacerbation of asthma with short courses of oral corticosteroids, A&E visits or hospital admission.

Overall, the carbon footprint attributed to asthma care when scaled to all patients in the UK was calculated at 750,540 tonnes CO2e/year.

But 47% of patients had poor asthma control which contributed to excess greenhouse gas emissions of 303,874 tonnes CO2e/year, they reported.

Around 90% could be attributed to inappropriate SABA use with the rest accounted for by GP and hospital visits, they reported.

If all aspects of asthma care were taken into account including routine management and prescribing, poorly controlled disease account for three times higher greenhouse gas emissions.

The NHS has set a target of cutting its direct carbon footprint by 80% by 2032, reaching net zero by 2040. Medicines account for a quarter of NHS emissions and asthma inhalers accounting for 3%.

Study leader Dr John Bell, global medical director biopharma respiratory at Astra Zeneca said: ‘Our study indicates that poorly controlled asthma contributes to a large proportion of asthma-care related greenhouse gas emissions with inappropriate SABA use emerging as the single largest contributor.’

He noted that The Global Initiative for Asthma (GINA) guidelines no longer recommend SABA used alone as the preferred reliever for acute asthma symptoms.

Long-awaited joint asthma guidance from NICE and the British Thoracic Society/ Scottish Intercollegiate Network (SIGN) is expected this year.

Dr Andy Whittamore, clinical lead at Asthma + Lung UK, said the study highlighted that high levels of uncontrolled asthma not only put thousands of people at risk of life-threatening asthma attacks, but also have a detrimental effect on the environment.

‘It’s important to point out that people shouldn’t stop taking their inhalers because they are worried about the environment – the best thing for the environment is to keep your asthma under control by taking your preventer inhaler as prescribed.

He added: ‘People with asthma need support to self-manage their condition in a way that works for them, ensuring they take their preventer inhaler according to a written action plan, have regular asthma reviews, and checks to ensure correct inhaler technique.’

This article was initially published by our sister title Pulse