Shift Practice

Environmental stewardship of pressurised metered-dose inhalers


Pressurised metered-dose inhalers (pMDIs) contain hydrofluorocarbon propellants


Pressurised metered-dose inhalers (pMDIs) contain hydrofluorocarbon propellants in which medicines are dissolved. They are liquids when under pressure and are released as a gas when the device is used. These hydrofluorocarbon compounds are potent global warming gases: 1350-3350 times more potent per gram than carbon dioxide.

More than 90% of the carbon footprint of these inhalers is due to these gases. In the UK, these gases are responsible for about 4% of the carbon footprint of the entire health service. The propellant gas in a typical salbutamol inhaler can cause as much warming as the tailpipe emissions from a car driving 300km.

There are other respiratory inhaler alternatives to pMDIs such as dry powder inhalers (DPIs) and soft mist inhalers (SMIs) which do not use these gases and consequently have much lower carbon footprints. In many countries, pMDIs are commonly used, despite high quality evidence that, for many patients, DPIs and SMIs would be equally efficacious.

Misdiagnosis of respiratory disease is also common, leading in some cases to overprescription of respiratory medicines. Their use and environmental impact are directly within the control of respiratory care providers and thus, exercising stewardship represents an important opportunity for positive change and leadership in healthcare environmental sustainability.

The health and safety of patients is paramount, but it is also important to recognise patient autonomy and involve them in these decisions.


Learn how to take action


Have patient focused conversations to find possible solutions:

Practitioners exercise stewardship in the use of pressurised metered dose inhalers (pMDIs), engaging in practices that reduce their use, when clinically safe to do so and at the same time recognising that many patients are willing to exercise sustainable choices where practical.

1. Acknowledge that many patients prefer pMDIs and some can’t do without them (safe treatment is the first priority).

2. Have a patient decision aid available such as the one provided below from the NHS in the UK.

3. If you are changing the inhaler type your patient is used to, remember to educate them on the new device and re-check inhaler technique at future consultations.

4. Don’t let this need for device education be a barrier to change. Many patients will find the change easy, and will appreciate being free of the need to use a spacer.

5. Patient safety is paramount in device choice and medication delivery. Informing patients and respecting patient autonomy can help people feel empowered by allowing a ‘guilt’-free choice. Patients are often keen to embrace choices that deliver more sustainable care.


All pressurised Metered Dose Inhalers (pMDIs) must have dose counters:

It is well recognised that Respiratory Inhalers improve the health of millions of patients and are vital in the treatment of common conditions such as Asthma and Emphysema. Patient wellbeing and improving their health outcomes is always of paramount importance to healthcare professionals. However, pMDIs currently contain propellant gases with very high global warming potentials, 1350-3350 times more potent per gram than carbon dioxide. The propellant gas in a typical salbutamol inhaler can cause as much warming as the tailpipe emissions from a car driving 300km.

Importantly recycling data from the UK shows that approximately half the doses are left in discarded pMDIs without dose counters and that even more concerningly many patients using pMDIs without dose counters unknowingly use empty inhalers!

Call on the regulatory bodies around the world to urgently demand that all pMDI’s be manufactured with dose counters to ensure that patients can recognise when inhalers are empty and additionally to avoid unknowingly disposing of partially used devices.

Take Further Action

Further ways to engage with this action


Reduce unnecessary use

1. First, think critically about your patient’s diagnosis. Do they need this respiratory medicine at all?

2. Optimise preventers to reduce PRN salbutamol use. In general optimising care will not only improve patient outcomes but have the greatest impact on reducing greenhouse gas emissions by reducing unnecessary use. Regularly review inhaler technique and encourage spacer use. Emphasise the importance of preventer/maintenance inhalers. Remember the importance of other approaches to improve disease control – smoking cessation support, pulmonary rehabilitation, vaccination for at-risk individuals.

Consider alternative devices when practicable

1. Is there a compelling reason to choose a pMDI?

2. Some people do better with MDIs, such as young children (especially under the age of 6), people with poor inspiratory capacity and those experiencing an acute exacerbation. But most people, even those with obstructive diseases, can breathe in sufficiently to use other inhalers.

Recycle inhalers

1. Plastic cases no-longer suitable for use should be recycled along with other hard plastic.

2. Pressurised canisters can be returned to the pharmacy for suitable disposal.

Support the development of low impact propellants by Industry

1. Innovation by industry is promising pMDIs with greatly reduced carbon footprints. These may eventually be helpful in those patients who cannot safely transition to inhalers other than MDIs.

Success Story

Learn from people's success


In many European countries dry powder inhalers (DPIs) have been and remain the norm — for example in Sweden, only about 10% of inhalers are  pressurised metered dose inhalers (pMDIs).

In terms of changing prescribing habits in countries with historically high MDI use, the United Kingdom is leading in awareness. Broadly, the UK aims to reduce health system emissions by 80% by around 2030, and to net zero by 2040.

Large-scale projects in the UK are underway  (in Hull and Stevenage) and involve systems for review of asthma patients who are overusing their salbutamol inhalers (~6 or more per year), checking their diagnosis, reviewing inhaler technique and optimising therapy, usually by offering to switch to maintenance and reliever therapy and prioritising dry-powder inhalers (DPIs) where they are clinically appropriate. This strategy targets those patients with the most symptoms, who also have the largest carbon footprint, and aims to optimise their treatment. Early evidence shows this strategy to be popular with patients, with big reductions in over-reliance on reliever inhalers (and therefore carbon footprint) and better compliance with controller therapies.

Further Reading

Resources to help you complete this action


1. Green inhaler: – a website about this issue by UK respiratory specialist Alex Wilkinson


2. Greener practice guide to inhaler prescribing:


3. British Thoracic Society: Position Statement on “The Environment and Lung Health 2020”. Particularly section 3:0 on “Low Carbon Inhalers”


4. “Carbon Footprint of choice of inhalers for asthma and COPD”

“How to reduce the Carbon Footprint of inhaler prescribing”


Some relevant videos:

1. From the UK:


2. From Australia:


3. An inhaler device decision aid from NICE (UK) incorporating environmental as well as clinical issues:


4. “How to” videos about respiratory inhaler devices – helpful for patient education:


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