In a new study, researchers at Uppsala University compared the carbon footprint of two kinds of inhaler used for treating asthma and chronic obstructive pulmonary disease: dry powder inhalers and sprays containing propellants. The results show that treatment with spray inhalers has a carbon footprint 20 times greater than that of using dry powder inhalers.

What causes the heavy environmental impact of asthma spray inhalers (metered-dose inhalers, MDIs) is the propellant they contain: hydrofluoroalkane, which has a greenhouse effect more than 1000 times stronger than carbon dioxide (CO2). Using a spray inhaler has a carbon footprint of 440 kg of CO2 per year and patient, against 17 kg from corresponding treatment with a dry powder inhaler (DPI). The difference in environmental impact between these two ways of treating asthma and chronic obstructive pulmonary disease (COPD) is close to the difference between following a vegetarian diet and living mainly on a meat-based one.

In 2017, 13 per cent of all inhalers used for asthma and COPD in Sweden were MDIs, while the corresponding figure for the United Kingdom was 70 per cent. Accordingly, the research team calculated that, theoretically, an annual reduction by 550,000 tonnes of CO2 would be attainable in the UK if, instead, a proportion of patients as high as in Sweden began using DPIs. This reduction corresponds to some 3 per cent of the National Health Service’s total carbon footprint.

In most cases, treatments with spray and powder inhalers are medically equivalent. However, there are some patient categories – especially among young children and certain older people – for whom spray is preferable.

”In the choice between a spray and a powder inhaler, factors like how easily a patient can use one or the other have to be included in the decision process. However, we’d like to emphasise that the difference in carbon footprint, too, is something to consider in choosing which type of inhaler to use for asthma and COPD,” says Professor Christer Janson of Uppsala University’s Department of Medical Sciences, Respiratory, Allergy and Sleep Research.

The Uppsala researchers collaborated in this study with colleagues from the UK and scientists from GlaxoSmithKline, the pharmaceutical company.

For further information, contact Christer Janson, tel. 46 70 425 0441, email

Janson C, Henderson R, Löfdahl M, Hedberg M, Sharma R, Wilkinson A. (2019) Carbon footprint impact of the choice of inhalers for asthma and COPD. Thorax, DOI: 10.1136/thoraxjnl-2019-213744.

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