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The impact of inhalers for asthma on the global climate: a systematic review of carbon footprint and clinical outcomes in Spain

Montoro J1, Antolín-Amérigo D2, Izquierdo-Domínguez A3, Zapata JJ4, González G5, Valero A6

1Sección de Alergia, Unidad Especializada de Asma Grave, Hospital de Líria, Facultad de Medicina, Universidad Católica de Valencia "San Vicente Mártir", Valencia, Spain
2Servicio de Alergia, Hospital Universitario Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain
3Servicio de Alergología, Consorcio Sanitario de Terrassa, Barcelona, Spain
4Clínica de Alergia Dr. Zapata, Almería, Spain
5Adelphi Targis, Barcelona, Spain
6Servicio de Alergología Hospital Clínic, IDIBAPS, CIBER de Enfermedades Respiratorias (CIBERES), Barcelona, Spain

J Investig Allergol Clin Immunol 2023; Vol. 33(4)
doi: 10.18176/jiaci.0887

Background: Pressurised metered-dose inhalers (pMDIs) exert some environmental impact due to their effect on CO2 emissions. There are other therapeutic alternatives with less environmental impact that are being widely used. Nevertheless, the choice of the device and the appropriate therapy should answer 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. Secondly, we aimed to evaluate the potential impact of switching pMDIs to dry-powder inhalers (DPIs) in patients with asthma.
Methods: Systematic review of the evidence published between 2010-2021 was carried out. Average annual CO2 emissions of DPIs and pMDIs were calculated in two scenarios: present 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 accounts for 0.0056% and 0.0909%, respectively, of total emissions in Spain. In the event of a conversion of all pMDIs to DPIs, except those for rescue medication, these percentages would be 0.0076% and 0.0579%. The evaluation of efficacy, handling, satisfaction, safety and healthcare resources utilization was not conclusive.
Conclusions: Current CO2 emissions derived from 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 or inspiratory flow should be prioritised at inhaler prescription.

Key words: Asthma, Inhaler devices, Metered-Dose Inhalers, Anti-Asthmatic Agents, Carbon Footprint, Climate change, Global warming, Environment