Table 3.

Strategies to reduce greenhouse gas emissions from MDIs

Strategy	Effect	Potential CO2e saving
Where appropriate, switch from MDI to non-propellant inhaler	Avoids use of HFA propellants.	8–36 kg per inhaler.
Change from large volume reliever (eg, Ventolin Evohaler) to small volume reliever (eg, Salamol)	Small volume reliever contains far less propellant.	18 kg per inhaler.
Change from HFA227ea inhaler (eg, Flutiform or Symbicort MDI) to HFA134a inhaler	Uses lower GWP HFA propellant.	20 kg CO2e per inhaler.
Recycle used MDIs	The plastics and aluminium are recycled and the HFA gas is captured for re-use.	Estimated 4–18 kg per inhaler, although potentially risks further atmospheric release of HFA by delaying incineration.
Return used inhalers to pharmacy after use	If the pharmacy cannot recycle the MDI, it will be incinerated. This causes thermal degradation of the HFA into chemicals with far smaller global warming potential.38	Likely to be slightly lower than recycling due to the energy inputs for incineration, and the absence of recycled materials. Estimated 3–17 kg per inhaler.
If there is no dose counter, ensure your patient knows how many doses the inhaler contains	Reduce waste from disposing of half-used inhalers.	Estimated to be a quarter of the inhaler’s carbon footprint; roughly 4 kg CO2e per inhaler.

GWP, global warming potential; HFA, hydrofluoroalkane; HFA134a, 1,1,1,2-tetrafluoroethane; HFA227ea, 1,1,1,2,3,3,3-heptafluoropropane; MDI, metered-dose inhaler.