South SFV Today

Each dose from an asthma inhaler, though seemingly insignificant, contains potent greenhouse gases that contribute to environmental pollution. A recent study published in JAMA by researchers from Stanford Medicine, the University of Michigan, and the National Health Service of England reveals that more than 70 million inhalers prescribed annually in the United States emit greenhouse gases equivalent to the yearly electricity use of 200,000 American homes.

The research team utilized data from the U.S. Centers for Medicare & Medicaid Services (CMS) to assess the types and quantities of inhalers prescribed to Medicare and Medicaid beneficiaries in 2022. The findings indicate a significant variation in emissions among different inhaler types. "There was a really wide range of emissions between different inhaler types," said Jyothi Tirumalasetty, MD, clinical assistant professor of pulmonary, allergy and critical care medicine at Stanford Medicine and first author of the paper. "In the U.S., we’re still mostly prescribing the inhalers that are the worst when it comes to emissions."

Inhalers typically contain medications such as bronchodilators to aid breathing for individuals with asthma or chronic obstructive pulmonary disease (COPD). There are three main types: metered-dose inhalers (MDIs), dry-powder inhalers (DPIs), and soft-mist inhalers (SMIs). European studies have shown that MDIs emit high levels of hydrofluorocarbon propellants, which significantly contribute to global warming. Consequently, countries like England, Sweden, and Canada have encouraged switching to DPIs and SMIs.

Tirumalasetty's team calculated the greenhouse gas emissions from 37 major inhalers used in the U.S., using safety data provided by manufacturers and CMS prescription data. They found that while DPIs and SMIs had minimal emissions, MDIs ranged from 9 to 48 kg of CO2 equivalent emissions per unit.

The study highlighted that MDIs accounted for 70% of nearly 70 million CMS inhaler claims in 2022 but contributed to 98% of total emissions attributed to inhalers. Despite their lower environmental impact, DPIs and SMIs are often more expensive than MDIs.

"This means that cost is potentially a barrier to the transition from metered-dose inhaler," Tirumalasetty noted. However, she emphasized that out-of-pocket costs for patients might not necessarily be higher for DPIs or SMIs.

The researchers hope their findings will prompt patients, providers, and policymakers to consider environmental impacts when choosing inhalers. Nonetheless, they acknowledge that individual patient needs must take precedence over environmental concerns.

"We don’t want to put patients in a place where they can’t afford their inhalers or where they’re using an inhaler that doesn’t work as well," Tirumalasetty stated.

Even at Stanford Medicine, changes in prescription practices based on these findings are still under consideration due to concerns about patient costs. The research team is working with Stanford Health Care to understand how costs affect patient preferences regarding inhalers.

"Ultimately, we’d like to have a nice, simple handout that tells patients what each inhaler costs and its emissions so they can decide," Tirumalasetty concluded.

Funding for this research was provided by the National Center for Advancing Translational Sciences and the U.S. Department of Veterans Affairs HSR Investigator-Initiated Research program.

Originally published by Stanford Medicine Scope.

© Copyright Stanford University. Stanford, California 94305.

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