The Problem with Inhalers

What has climate change got to do with inhalers?

Many people are surprised to learn what a big contribution inhalers make to their carbon footprint. The most commonly used inhalers in the UK are called Metered Dose Inhalers (MDIs). These typically have a metal canister which you push down into a plastic case to release a puff of medicine into your lungs while you breathe in.

MDI on side
Example of a metered dose inhaler

Their main ingredient is a hydrofluorocarbon gas, which helps deliver the medicine into your lungs. Hydrofluorocarbons (HFCs) are powerful greenhouse gases – thousands of times more potent than carbon dioxide.

We used to use Chlorofluorocarbons (CFCs) in metered dose inhalers. These were banned after we realised what a big impact they were having on the ozone layer. CFCs are also potent greenhouse gases, and climate change would be far worse today if we hadn’t acted promptly when we did to ban their use. HFCs don’t damage the ozone layer, but they are powerful greenhouse gases, far more powerful than carbon dioxide which is the most abundant and important greenhouse gas.

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Greenhouse Gas effect (global warming potential or GWP) of HFA 227ea, HFA134a which is used in most inhalers, and CO2 which is the most abundant greenhouse gas.

Your inhaler can have a big impact on your carbon footprint. The most commonly used inhaler in the UK, Ventolin Evohaler™ has a carbon footprint of 28kg per inhaler. That’s the same carbon footprint as the tailpipe greenhouse gas emissions of driving 175miles (or from London to Sheffield) in a small car. Dry powder inhalers on the other hand typically have a carbon footprint of less than 1kg.

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Equivalent tailpipe greenhouse gas emissions from 1 Ventolin Evohaler (containing 100 2-puff doses) and 1 Ventolin Accuhaler (60 1-puff doses). Evohaler is 28kg CO2e per inhaler, accuhaler is 0.6kg CO2e. Evohaler has no dose counter and on average half the doses are wasted. Assumes car achieves 100gCO2/km.

Changing the type of inhalers you use, could reduce your carbon footprint as much as becoming vegetarian.

Greenhouse gas impact of various recommended actions (based on mean values from Wynes and Nicolas 2017 Envriron. Res. Let. 12 091001) compared to some inhaler switches. Assumes one of each inhaler used monthly. DPI=Dry Powder Inhaler.

What exactly is the carbon footprint of my inhaler?

Unfortunately most drug companies are reluctant to talk about this, and we don’t have as much information as we would like. We do have accurate, published information on some inhalers, and other information has been gleaned from patents and other scientific studies to estimate the carbon footprint of inhalers. Some inhalers (Flutiform™ and Symbicort™ metered dose inhaler*) use a particularly damaging hydrofluorocarbon (HFA227 rather than HFA134) which gives them a far greater carbon footprint. We do know that ~97% of the carbon footprint of inhalers comes from their HFA propellant, so where we know the volume and type of propellant in an inhaler, we can make a good estimate of its carbon footprint.

Dry powder inhalers have a far smaller carbon footprint, generally estimated to be less than one kilo and there are some independently certified carbon footprinting studies confirming this – 10_Environmental_Impact_of_Inhalers

*NB the most commonly used Symbicort is the turbohaler. The Turbohaler™ dry powder inhaler with a small carbon footprint.

Are there alternatives to these metered dose inhalers?

For many patients, effective and more environmentally-friendly alternatives are available such as dry-powder inhalers. You can learn more about them here.