Inhaler-Related Greenhouse Gas Emissions in the US: A Serial Cross-Sectional Analysis.

Area of Science:

• Environmental Science
• Public Health
• Pharmaceutical Science

Background:

• Inhalers are essential for asthma and COPD management.
• Metered-dose inhalers (MDIs) utilize hydrofluoroalkane propellants, contributing significantly to greenhouse gas emissions.
• US hydrofluorocarbon phasedown necessitates understanding inhaler-related emissions.

Purpose of the Study:

• To quantify the magnitude, sources, and social costs of inhaler emissions in the US from 2014 to 2024.
• To analyze trends in inhaler utilization and associated environmental impact.
• To inform policy decisions regarding emission reduction strategies.

Main Methods:

• Serial cross-sectional analysis of aggregated US outpatient pharmaceutical dispensing data (2014-2024).
• Estimation of greenhouse gas emissions (CO2e) linked to specific inhaler products.
• Characterization of inhalers by active ingredients, device type, propellant, and therapeutic class.

Main Results:

• 1.6 billion inhalers dispensed, generating 24.9 million metric tons of CO2e.
• Annual emissions rose by 24% over the decade.
• MDIs accounted for 98% of emissions, with specific short-acting β-agonist and inhaled corticosteroid combinations being major contributors.
• Estimated social costs of emissions reached $5.7 billion.

Conclusions:

• US inhaler-related emissions have significantly increased.
• Targeted strategies are needed to transition to lower-emission inhaler types (dry powder, soft mist).
• Facilitating newer, low-global warming potential propellant MDIs is recommended.