Climate pollution from inhalers has the impact of half a million cars per year, study finds.

         by Arup Sarkar

Research article: https://jamanetwork.com/journals/jama/fullarticle/2822997

News article: https://www.cnn.com/2025/10/06/health/inhalers-climate-change-wellness

Background

HFAs, which are commonly used as refrigerants and aerosol propellants, were introduced as substitutes for ozone-depleting substances such as chlorofluorocarbons (CFCs). Although they do not damage the ozone layer, they are strong greenhouse gases with high global warming potentials (GWPs); for instance, HFA-134a traps a lot more heat per molecule than carbon dioxide¹, with a GWP of about 1,430. Even though they are released in lesser amounts, HFAs may be measured for their contribution to radiative forcing and global warming and remain in the atmosphere for years⁴. The Kigali Amendment to the Montreal Protocol (2016) mandates a global phase-down of HFA production and use in recognition of their impact on the climate; if fully implemented, this could prevent warming of up to 0.5°C by 2100^2,3.

Research article

Pressurized metered-dose inhalers (pMDIs), which are frequently recommended to treat asthma and chronic obstructive pulmonary disease (COPD), administer medication to the lungs using hydrofluorocarbon (HFC) propellants. The global warming potentials (GWPs) of these propellants can be thousands of times higher than those of carbon dioxide, which means that each molecule traps a lot more heat in the atmosphere, despite their effectiveness as a therapy. Consequently, inhaler devices have a significant impact on global warming, although their carbon footprint and expenses have not been well quantified in the United States. In the article "Greenhouse Gas Emissions and Costs of Inhaler Devices in the US" by Tirumalasetty et al., published in  "JAMA," the authors assessed the mean greenhouse gas emissions (in CO₂ equivalent units) per inhaler device as well as the total annual emissions from inhalers prescribed under Medicare Part D and Medicaid in 2022, along with the related costs.

 The devices were classified as metered-dose inhalers (MDIs), dry-powder inhalers (DPIs), and soft-mist inhalers based on published propellant/packaging information and data. The authors collected 2022 prescription claims for branded inhalers from the CMS (Centers for Medicare & Medicaid Services) databases (Medicare Part D + Medicaid). They calculated emissions per device by integrating manufacturing and active pharmaceutical ingredient (API) emissions extrapolated from European research with inhaler weight, propellant %, and the propellant's 100-year global warming potential (GWP) as reported by the IPCC. Furthermore, Costs per claim were also extracted. To get total emissions, they then multiplied mean emissions by the number of claims for each device class.

 

They discovered a significant difference in mean emissions per inhaler by device class: MDIs averaged 23.1 kg CO₂‑equivalent (CO₂e) (SD 11.3) per inhaler, while DPIs and soft-mist inhalers only averaged ~0.79 and ~0.78 kg CO₂e, respectively. At about 48.1 kg CO₂e, the MDI (Dulera) had the greatest single-device emissions, whereas the corresponding DPI (Advair Diskus) emitted approximately 0.898 kg CO₂e. Approximately 69.8 million inhaler claims (CMS population) contributed to an expected 1.15 million metric tons (MMT) of CO₂e in 2022; MDIs alone were responsible for approximately 1.13 MMT (≈ 98.3% of inhaler-related emissions), spanning approximately 49 million claims (~70.2%). Soft-mist and DPIs contributed a higher percentage of spending ($10 billion for DPIs = ~50.8% of cost vs. 24.5% of claims) than they did to emissions.

 

Table.  Estimated Greenhouse Gas Emissions, Costs, and Number of Claims of US Inhalers by Device Class Among Medicare Part D and Medicaid Beneficiaries in 2022.

Figure.  Claims, Estimated Greenhouse Gas Emissions, and Spending for All Inhalers Filled by Medicare Part D and Medicaid Beneficiaries in 2022 by Device Class.

The authors interpret these findings to suggest that a significant amount of greenhouse gas emissions from the U.S. health-care system is caused by inhaler devices, especially those that use HFA propellants. The disproportionately higher emissions from MDIs compared to propellant-free alternatives indicate that, despite the importance of inhalers for patient care, there may be a chance to mitigate climate change with a high impact by changing prescribing patterns toward lower-emission device types (when clinically appropriate). They mention the cost-paradox as well: Soft-mist and DPIs offer significantly reduced emissions; however, they are sometimes more costly, which may prevent substitution.

The study's reliance on CMS data (Medicare Part D + Medicaid) limits its ability to fully reflect the entire national inhaler market, which includes those with private insurance and those without. Furthermore, manufacturing/API emissions may not accurately reflect situations in the United States because they were calculated using data from European studies. In their conclusion, the authors advise that formulary choices and device design take environmental impact into account in addition to clinical efficacy and cost. They also recommend more research into low-GWP, cost-effective inhaler technologies and ways to change usage without sacrificing patient outcomes.

News article

I would rate this news article an 8 out of 10. The headline — “Climate pollution from inhalers has the impact of half a million cars per year, study finds” — is striking and immediately captures attention. In light of the escalating environmental concerns, the article effectively summarizes the  paper's findings and emphasizes the vital function inhalers play in the management of chronic lung disorders. Crucially, it makes clear that the hydrofluoroalkane (HFA) propellants used in some inhalers—rather than the drug itself—are the source of the environmental risk. The statement that emissions from inhalers are equivalent to powering 470,000 homes or more than half a million cars struck me as a particularly powerful quote that effectively conveyed the scope of the issue. The article also accurately points out that HFAs have a major role in global warming, even if they don't damage the ozone layer.However, the paper does not provide a critical critique of the research itself. It omits the caveat that the study only looked at inhalers prescribed by CMS programs, not those purchased by privately insured or uninsured people. It also fails to address the potential unreliability of using European data to estimate active pharmaceutical ingredient (API) emissions. Despite these omissions, the piece effectively explains the overall environmental concerns to a broad readership.

Citations

1. Safeguarding the Ozone Layer and the Global Climate System: Issues Related to Hydrofluorocarbons and Perfluorocarbons (Cambridge Univ Press, New York, 2005.

2. Velders, G. J. M.; Fahey, D. W.; Daniel, J. S.; Andersen, S. O.; McFarland, M. Future Atmospheric Abundances and Climate Forcings from Scenarios of Global and Regional Hydrofluorocarbon (HFC) Emissions. Atmos. Environ. 2015, 123, 200‑209. DOI: 10.1016/j.atmosenv.2015.10.071.

3. Velders, G. J. M.; Daniel, J. S.; Montzka, S. A.; Vimont, I.; Rigby, M.; Krummel, P. B.; Mühle, J.; O’Doherty, S.; Prinn, R. G.; Weiss, R. F.; Young, D. Projections of Hydrofluorocarbon (HFC) Emissions and the Resulting Global Warming Based on Recent Trends in Observed Abundances and Current Policies. Atmos. Chem. Phys. 2022, 22, 6087‑6107. DOI: 10.5194/acp‑22‑6087‑2022.

4. https://www.thermal-engineering.org/hydrofluorocarbons-refrigerants-global-warming-potential