D26-15 Inhaler-Associated Greenhouse Gas Emissions in an Academic Medical Center Pulmonary Clinic: A Descriptive Study

Abstract Rationale Metered-dose inhalers (MDIs) and dry powder inhalers (DPIs) are the most common forms of medicated inhalers, with MDIs representing 88% of inhaler sales in the US in 2020.1 MDIs historically used chlorofluorocarbons (CFCs) as propellants; however, these were replaced by hydrofluorocarbons (HFCs) to avoid CFCs’ ozone-depleting effects.1 However, HFCs are potent greenhouse gases (GHGs) with about 1,400 to 3,200 times the heat-trapping potential of carbon dioxide.1 The US Environmental Protection Agency estimated that in 2020 alone, 2.5 million metric tons of carbon dioxide equivalents (CO2e) of HFCs were contained in MDIs sold across the US.1 On the other hand, DPIs emit negligible GHGs, with a lifecycle carbon footprint 12 to 200 times lower than that of MDIs.2 Moreover, for patients with adequate inspiratory flow, DPIs have demonstrated therapeutic efficacy similar to MDIs in treating COPD and asthma.3 Therefore, health systems and providers can reduce inhaler-related GHG emissions without compromising patient care. Such efforts are essential in the U.S., where our health system accounts for approximately a quarter of global healthcare-related GHG emissions, and where many patients are increasingly at risk of adverse cardiopulmonary outcomes from exposure to climate-related hazards.4,5 We conducted a pilot study on inhaler prescribing practices at a quaternary care center in Colorado to guide future interventions to mitigate the GHG emissions associated with outpatient asthma and COPD care. Methods Inhaler prescription counts at the University of Colorado Pulmonology Clinic from 1/1/2024 to 12/31/2024 were extracted using the SlicerDicer tool in Epic. The CO2e of each inhaler was calculated using the methodology described in Tirumalasetty et al.6 Results A total of 30,339 inhalers were prescribed during the study period. 18,477 (61%) of these were MDIs, 9,051 (30%) were DPIs, and the remaining 2,811 (9%) were soft mist inhalers (Table 1). The total estimated CO2e from all inhaler prescriptions in the study year was 455,771 kg, equivalent to burning about 500,000 lbs of coal.7 MDI inhalers accounted for 446,278 kg of CO2e (98%) despite making up only 61% of total prescriptions. Changing 10% of MDIs to DPIs would eliminate 43,166 kg of CO2e, which is equivalent to the CO2e of 10 gas-powered vehicles driven for one year.7 Conclusion In this single-center descriptive study, MDIs were the most prescribed inhaler device and accounted for the vast majority of inhaler-related GHG emissions. At scale, changes in prescribing practices for airway diseases could lead to substantial reductions in inhaler-associated GHG emissions. This abstract is funded by: None