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Metered dose inhalers Climate-relevant therapy

The therapy of asthma and COPD is climate-relevant

The majority of dermatologists are familiar with the diagnosis and treatment of allergic diseases of the upper respiratory tract such as rhinoconjunctivitis allergica and asthma. Seasonal shifts and prolongation of the pollen season caused by climate change have Allergic respiratory diseases have increased sharply since the 1980s.which affects the frequency of prescribing DAe and PI.

Daily medication against allergic asthma is prescribed in two different forms of application, among others:

  1. Metered dose inhalers (DAe) are applied to the mouth. By applying pressure to the trigger, a propellant with active ingredient is delivered into the respiratory tract with simultaneous inhalation.
  2. Powder inhalers (PI) are enclosed by the mouth. Inhalation takes place by suction during 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 Methanenitrous oxide and man-made 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 as that of carbon dioxide. The Dwell time in the atmosphere is in some cases between a few decades and several hundred years. Worldwide, they contribute around two per cent to the greenhouse effect and thus about as much as international air traffic. Previous research has shown, for example, that DAe prescribed in England contribute 3.9 % to the carbon footprint of the UK National Health Service. In Germany, F-gas emissions already accounted for Federal Environment Agency accounts for about 1.6 per cent of greenhouse gas emissions.

The F-gases used in asthma spraysmostly the tetrafluoroethane HFA 134a and the heptafluoropropane HFA 227ea, are potent greenhouse gases and can cause up to 1.430 resp. 3.220 times more potent than carbon dioxide.

Comparison of metered dose inhalers (DAe) - powder inhalers (PI)

If we now compare the carbon dioxide balance of DAe with PI, that of PI up to 20 times better as which DAe.

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 DAe and PI.

* In Studies it was shown that the effectiveness of the respective systems DAe versus PI does not depend on the type of drug, but on the correct application.

** cf.

Recommendation for the prescription of asthma medication:

  • Consider prescribing 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 climate balance.
  • When using MDIs as an emergency medication or for elderly people, careful information should be provided not only on their use but also on their disposal.
  • Note the propellants in metered dose inhalers, as these differ significantly in terms of their carbon footprint.
  • Metered dose inhalers dispose of correctlyas residual gases escape after the end of use and the inhalers are dangerous goods.
  • Disposal services for medicines depend on the municipality. Here you will find further information


Update: S2k guideline "Climate-conscious prescription of inhalants" 1/24

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

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