Carbon footprint

Pressurised metered dose inhalers (pMDI) contain hydrofluorocarbon (HFC) propellants that do not have an effect on the ozone layer but are powerful greenhouse gases and can contribute to global warming.

Dry powder inhalers (DPI) do not use these propellants and have substantially lower global warming potential, producing 20g CO₂ equivalent (CO₂eq) per dose compared with 500g CO₂eq for some pressurised metered dose inhalers.

Estimated carbon footprints for comparison indicate an average trip (9 miles) in a typical car produces 2,610g CO₂eq (or 290g CO₂eq per mile).

As Breath Actuated Inhalers (BAIs) contain the same propellants as pMDIs, the estimated carbon footprints for pMDIs can reasonably be extrapolated to BAIs. Available data consistently show that there is a significant difference between DPIs and pMDIs / BAIs, and due to the absence of HFC propellants, DPIs have a low carbon footprint compared to other inhalers.

The Respimat device is a soft mist inhaler (SMI) that does not contain propellants, and so also has a lower carbon footprint than pMDIs and BAIs.

pMDI use in England is responsible for nearly 1 million tonnes of CO₂ equivalent per year.

The NHS Long Term Plan identifies a shift to lower carbon inhalers as a way of significantly reducing the carbon footprint of health and social care.

With this in mind, dry powder inhalers or soft mist inhalers are generally preferred locally, unless there is a specific clinical or dexterity reason that an individual requires a pMDI or BAI.

In young children, a pMDI and a spacer is the preferred method of delivery; a face mask is required until the child can breathe reproducibly using the spacer mouthpiece. A pMDI plus spacer is also recommended for patient of any age for the treatment of mild and moderate acute asthma attacks. Other factors to consider include the choice of drug, patient preference, and acquisition cost.

NICE has produced a patient decision aid to help people with asthma and their healthcare professionals discuss their options for inhaler devices (available here), which includes consideration of the carbon footprint of the inhaler. It is suitable for use by people aged 17 years and over, and many of the considerations are also applicable to patients with COPD.

Carbon footprint comparison tables

Data on the actual carbon footprint of individual inhalers is very limited, therefore the following tables provide indicative rather than actual values. The figures are based on usual daily doses recommended in the Devon Formulary and median CO₂eq values per inhaler as estimated by PrescQIPP. Equivalent care miles for comparison have been estimated on the basis of an average trip (9 miles) in a typical car producing 2,610g CO₂eq (or 290g CO₂eq per mile) (see NICE).

These figures are intended to highlight the environmental impact of inhaler devices containing hydrofluorocarbon (HFC) propellants compared to dry powder / soft mist inhalers. When relevant clinical factors have been taken into account, the potential environmental benefits of selecting products with lower CO₂eq per puff and/or dosing regimens that require fewer puffs per day are also noted.

Short acting beta-agonists (SABA)

Dry Powder inhalers (DPI)

Pressurised metered dose inhalers (pMDI) and breath-actuated inhalers (BAI)

Ventolin Evohaler 100 micrograms is a non-formulary product. The CO₂eq per puff is 141 grams. The equivalent annual car miles for a daily dose of up to 8 puffs is up to 1,420 car miles.

Long acting beta agonists (LABA)

Dry Powder inhalers (DPI)

Pressurised metered dose inhalers (pMDI)

Short acting muscarinic agonists (SAMA)

Pressurised metered dose inhalers (pMDI)

Long acting muscarinic antagonists (LAMA)

Dry Powder inhalers (DPI) and Soft Mist Inhalers (SMI)

Combination inhalers: Inhaled corticosteroid (ICS) + Long acting beta2 agonists (LABA)

Dry Powder inhalers (DPI)

¹ estimates do not include additional “prn” use as part of MART regimens; ² first line for COPD

Pressurised metered dose inhalers (pMDI)

¹ estimates do not include additional “prn” use as part of MART regimens

Combination inhalers: Long-acting beta2 agonists (LABA) + Long-acting muscarinic antagonists (LAMA)

Dry Powder inhalers (DPI) and Soft Mist Inhalers (SMI)

Triple combination inhalers: Inhaled corticosteroid (ICS) + Long-acting beta2 agonists (LABA) + Long-acting muscarinic antagonists (LAMA)

Dry Powder inhalers (DPI)

Pressurised metered dose inhalers (pMDI)

Corticosteroids

Dry Powder inhalers (DPI)

Pressurised metered dose inhalers (pMDI) and breath-actuated inhalers (BAI)

Waste and recycling

Used pMDI canisters still contain propellants; all used pMDI canisters should be returned to a pharmacy (or dispensing GP practice) to dispose of in an environmentally safe way.

Used inhalers should not be placed in general waste.

Used inhalers that are not returned to pharmacies but are placed in general waste for kerbside collection may end up in landfill, depending on local authority arrangements. As well as plastic pollution, this risks crushing or piercing the pMDI / BAI canister and releasing additional propellants into the atmosphere.

Inhalers should be placed in the pharmacy's pharmaceutical waste bins, which are incinerated (destroying the greenhouse gases); steel and aluminium may be recovered and recycled at some incinerators. Spacers cannot currently be recycled.