Reducing the impact of asthma treatment on climate change

In April 2019, the National Institute for Health and Care Excellence (NICE) published a patient decision aid for inhaler choice in asthma treatment, including comparisons of the devices’ environmental impact as well as usual clinical considerations[1]
. The aid suggests taking inhalers’ carbon footprint into account when choosing a device if this is a clinical option for the patient.

The patient decision aid comes as a reaction to the ‘NHS Long Term Plan’, which was published in January 2019 and recommended a greater emphasis on environmentally friendly approaches in the health service.

Metered dose inhalers (MDIs) use hydrofluorocarbons (HFCs) — potent greenhouse gases — as propellants (in which the active ingredient is suspended). Hydrofluorocarbon (HFC)-134a (or 1,1,1,2-tetrafluoroethane), the most commonly used HFC, has a global warming potential of 3,710 over 20 years, meaning that HFC 134a is 3,710 times more potent than carbon dioxide in this regard[2]

Just five doses from an MDI have a global warming potential equivalent to a nine-mile trip in a typical car, with each dose having an estimated carbon footprint of the equivalent of 500g of carbon dioxide[2]
. By comparison, dry powder inhalers (DPIs) have a carbon footprint of 20g of carbon dioxide equivalent per dose.

Around 70% of inhalers used in the UK are MDIs, compared with around 10% in Sweden, suggesting that there is considerable scope to increase the use of DPIs in the UK[3]

Pharmacists could play their part in integrating this guidance into primary care by helping patients understand the environmental impact of their MDIs, so that they can have an informed discussion with their clinician at their next asthma review. This could take place during medicines use reviews or as opportunities arise.

Any reduction in carbon emissions as a result of professional interactions between pharmacists and patients is good news while we collectively work to tackle climate change, and its impacts (including impacts on health). In 2018, a World Health Organization assessment concluded that climate change is expected to cause approximately 250,000 additional deaths per year between 2030 and 2050; 38,000 resulting from heat exposure in older people, 48,000 resulting from diarrhoea, 60,000 resulting from malaria, and 95,000 resulting from childhood undernutrition[4]

The UK, which will be relatively sheltered from these effects, should surely do what we can to minimise them.

The patient decision aid can be found at:


Andrew Baker, practice pharmacist, Ebbw Vale


[1] National Institute for Health and Care Excellence. Patient decision aid inhalers for asthma. 2019. Available at: (accessed June 2019)

[2] Stocker TF, Qin D, Plattner G-K et al. Climate Change 2013: The Physical Science Basis. Working Group I Contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press. 2013. Available at: (accessed June 2019)

[3] Hillman T, Mortimer F & Hopkinson NS. Inhaled drugs and global warming: time to shift to dry powder inhalers. BMJ 2013;346. doi: 10.1136/bmj.f3359

[4] World Health Organization: Fact sheet: Climate change and Health. 2018. Available at: (accessed June 2019)

Last updated
The Pharmaceutical Journal, PJ, June 2019, Vol 302, No 7926;302(7926):DOI:10.1211/PJ.2019.20206606