Impact of Asthma Inhalers on Global Climate: A Systematic Review of Their Carbon Footprint and Clinical Outcomes in Spain.

BACKGROUND: Pressurized metered-dose inhalers (pMDIs) exert an environmental impact resulting from CO2 emissions. Therapeutic alternatives with less environmental impact are widely used. Nevertheless, the choice of device and appropriate therapy should meet the clinical needs and the characteristics of the patient.

OBJECTIVE: The primary objective was to estimate the impact of pMDIs prescribed for any indication on annual CO2 emissions in Spain.The secondary objective was to evaluate the potential impact of switching pMDIs to dry-powder inhalers (DPIs) in patients with asthma.

METHODS: A systematic review of the evidence published during 2010-2021 was carried out. Average annual CO2 emissions of DPIs and pMDIs were calculated in 2 scenarios: the current situation and a hypothetical situation involving a switch from all pMDIs to DPIs. The impact of the switch on clinical outcomes was also evaluated.

RESULTS: The total value of CO2-eq/year due to DPIs and pMDIs accounted for 0.0056% and 0.0909%, respectively, of total emissions in Spain. In the event of switching pMDIs to DPIs, except those used for rescue medication, the percentages were 0.0076% and 0.0579%. The evaluation of efficacy, handling, satisfaction, safety, and use of health care resources was not conclusive.

CONCLUSIONS: Current CO2 emissions by pMDIs account for a small percentage of the total CO2 footprint in Spain. Nevertheless, there is a need for research into new and more sustainable devices. Suitability and patient clinical criteria such as age and inspiratory flow should be prioritized when prescribing an inhaler.