Carbon Footprint of Inhaled Therapy in Routine Healthcare: A Six-Year Population- Based Study of Dispensing Data

Background Healthcare decarbonisation requires reliable indicators capable of identifying the clinical practices and technologies responsible for greenhouse gas emissions. Inhaled therapies are particularly relevant because pressurised metered-dose inhalers contain propellants with a substantially greater climate impact than propellant-free devices. However, longitudinal evidence based on routine dispensing data remains limited. This study examined temporal changes in inhaler dispensing and associated carbon emissions between 2020 and 2025 and evaluated the potential of routinely collected pharmaceutical data to support population-level monitoring of sustainable respiratory care. Methods A retrospective, region-wide observational study was conducted using administrative dispensing data from a regional public healthcare system in north-western Spain. All inhalers dispensed through community pharmacies and reimbursed by the public healthcare system between 1 January 2020 and 31 December 2025 were included. Devices were classified as pressurised metered-dose inhalers (pMDIs), dry powder inhalers (DPIs), or soft mist inhalers (SMIs) and grouped by therapeutic class. Carbon emissions were estimated by multiplying the number of devices dispensed by product-specific emission factors expressed as kg CO₂e per inhaler. Annual dispensing patterns and estimated emissions were analysed descriptively by device type, therapeutic group, and calendar year. Results A total of 1,250,943 inhalers were dispensed during the six-year study period, generating an estimated cumulative carbon footprint of 9.27 million kg CO₂-equivalent. Although pMDIs represented 38.7% of dispensed devices, they accounted for 93.8% of total estimated emissions. Short-acting β₂-agonists were the largest therapeutic contributor, accounting for 46.5% of overall emissions. Annual dispensing volumes remained relatively stable, whereas estimated emissions increased from 1.45 million kg CO₂-equivalent in 2020 to a peak of 1.67 million kg in 2023, before declining to 1.52 million kg in 2025. Conclusions The environmental impact of inhaled therapy was determined primarily by inhaler technology and therapeutic composition rather than overall dispensing volume. Routine dispensing data may provide healthcare systems with a practical indicator for monitoring the environmental performance of respiratory care and identifying priorities for clinical review. When therapeutically appropriate, inhaler selection, optimisation of maintenance treatment, inhaler technique assessment, adherence support, patient education, and shared decision-making may contribute to healthcare decarbonisation without compromising safe, effective, and person-centred respiratory care. Implications for nursing management and practice Routine dispensing data can help nursing managers and clinical teams identify inhaler technologies and therapeutic groups associated with the greatest environmental burden and incorporate measurable sustainability indicators into respiratory care governance. Nurses can translate these population-level findings into person-centred practice through inhaler technique assessment, adherence support, patient education, decision-making about clinically appropriate inhaler options. Integrating carbon literacy with pharmaceutical monitoring may support environmentally responsible respiratory care without compromising treatment effectiveness, patient safety, or individual preferences.