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Metered dose inhalers
Climate-relevant therapy

Asthma and COPD therapy is climate-relevant

The majority of dermatologists are familiar with the diagnosis and treatment of allergic diseases of the upper respiratory tract, such as allergic rhinoconjunctivitis and asthma. Climate change-induced seasonal shifts and lengthening of the pollen season have greatly increased allergic respiratory diseases since the 1980s, which has had an impact on the frequency of prescriptions for MDIs and DPI.

Daily medication against allergic asthma is prescribed in two different forms:


  1. Metered Dose Inhalers (MDI) are administered into the mouth. By applying pressure to the trigger, a propellant with active ingredient is delivered into the respiratory tract with simultaneous inhalation.

  2. Dry powder Inhalers (DPI) are enclosed by the mouth. Inhalation takes place by suction accompanied by rapid inhalation.

Propellants of metered dose inhalers are more harmful to the climate than powder inhalers

In addition to the greenhouse gas carbon dioxide, whose share has risen sharply since industrialisation, other greenhouse gases such as methane, nitrous oxide and artificially produced fluorinated greenhouse gases (F-gases) are released into the atmosphere. F-gases do not affect the ozone layer, unlike CFCs, whose production has been banned worldwide since 2020.

F-gases are not only found in products such as freezers, air conditioners, fire extinguishers and insulation materials, but also in asthma sprays. The global warming potential of these gases is about 100 to 23,000 times higher than that of carbon dioxide. Some of them remain in the atmosphere for between a few decades to several hundred years. Globally, they contribute about two per cent to the greenhouse effect, about the same as international aviation. Previous research has shown, for example, that MDIs prescribed in England contribute 3.9% to the carbon footprint of the UK National Health Service. In Germany, F-gas emissions alone accounted for about 1.6% of greenhouse gas emissions in 2014, according to the Federal Environment Agency.

The F-gases used in asthma sprays, mostly the tetrafluoroethane HFA 134a and the heptafluoropropane HFA 227ea, are strong greenhouse gases and up to 1,430 and 3,220 times more potent than carbon dioxide, respectively.

Comparison of metered dose inhalers (MDIs) and dry powder inhalers (DPIs)

If we compare the carbon dioxide balance of MDIs with DPIs, DPIs are up to 20 times better than MDIs.

Most of the active substances and combinations of active substances that play a role in the therapy of asthma and COPD are available both as MDIs and DPIs.

Table dosage aerosols.png

* Studies have shown that the efficacy of the MDIs versus DPIs does not depend on the type of drug, but on the correct application.


Recommendation for the prescription of asthma medication:


  • Consider prescribing dry powder inhalers if a deep breath of 2-3 seconds or a longer breath of 4-5 seconds is possible, as these have a much better carbon footprint.

  • When metered dose inhalers are used as an emergency medication or for elderly people, careful information should be provided not only on their use but also for their disposal.

  • Note the propellants in metered dose inhalers, as these differ significantly in terms of their carbon footprint.

  • Treibmittel in Dosieraerosolen beachten, da diese sich in der Klimabilanz deutlich unterscheiden.

  • Dispose of metered dose inhalers correctly, as residual gases escape at the end of use and the inhalers are hazardous materials.

© Dr. med. Christina Hecker and Dr. med. Dipl. Biol. Susanne Saha 07/2021



Update: "Arznei-Telegramm" from November 2021

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