Climate pollution from inhalers has the impact of half a million cars per year, study finds.
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 21002,3.
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.
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
Hi Arup, I really enjoyed reading your analysis. I find it really interesting that such a large impact caused by a common medical device is less known. I wonder if the numbers would change once accounting for privately-insured or uninsured purchased inhalers. I know there are nebulizers, which are bulkier than inhalers and take more time to use, but I believe they are more effective at helping a patient with asthma. I wonder if further research can be done on that front to make the nebulizer more compact and fast acting, or if the nebulizer works the same way and if so, how does it affect the greenhouse gases.
ReplyDeleteHello, Elizabeth
DeleteThank you for your feedback. I suppose the results may change if we consider inhalers purchased by privately insured or uninsured individuals. MDIs are typically the least expensive choice; however, they also have the biggest environmental effect due to greenhouse gas emissions. People are more prone to use MDIs because they are less expensive, which may considerably contribute to global warming.
To my understanding, nebulizers do not require propellants; hence, their carbon impact is lower than that of MDIs. I'm not sure how helpful nebulizers are for chronic disorders other than asthma, but I feel further research should be done to see how they may be used for such purposes.
Hi Arup, thank you for sharing such an interesting study! I didn't realize that inhalers contained HFAs; it makes me wonder how many other products contain these propellants. The authors of the peer-review article mention that inhalers with lower emissions of GHGs are more expensive, which may force people to choose the less expensive MDIs that are worse for the environment. I think another good strategy for lowering the climate impacts associated with inhaler usage would be efforts to lower the cost of DPIs and soft-mist inhalers. If cost wasn't an issue, people may choose DPIs and soft-mist inhalers over MDIs when possible, leading to lower emissions of HFAs. Developing new propellants for MDIs may take time and increase the cost of those inhalers. Lowering the cost of alternatives is an option that could lead to a faster decrease in GHG emissions associated with inhaler usage.
ReplyDeleteHi, Sophie, Thank you for your remark. Dry powder inhalers (DPIs) and soft mist inhalers are often more expensive for a variety of reasons. These include the lack of generic manufacturing paths, more complex and specialized production techniques, increased R&D expenses, and continuous patent-related issues. Furthermore, the technology used in these inhalers is very new, limiting large-scale production and cost savings.
DeleteMetered-dose inhalers (MDIs), on the other hand, have been available for several decades and are manufactured according to well-established standards. Years of refining have resulted in more efficient and cost-effective manufacturing processes, making MDIs a more economical option in comparison. This cost differential is one of the primary reasons MDIs are still widely used, despite their higher environmental impact.
Hi Arup, this was an interesting topic to learn about! I really liked that the news story implicitly addressed climate feedback loops with its opening discussion on climate change leading to poorer air quality and more inhaler use. I'd be curious to know if any study has addressed this feedback loop more fully, by investigating the expected increase in chronic lung diseases and corresponding increase in inhaler emissions due to climate change. I was really shocked at how substantial the emissions were from inhaler propellants, because I don't often consider the medical sector as a source of greenhouse gases. I agree with you that comparing the quantity of inhaler emissions to more familiar metrics like home energy usage or car emissions is really helpful in conceptualizing the problem. I also appreciated that the CNN article included quotes from the study's authors and other researchers to explain why these emissions are a good target for action, as opposed to bigger greenhouse gas sources, as that's a question I had while reading the JAMA article.
ReplyDeleteHi Arup, this was a great read and review. HFAs were definitely something that I did not consider within the scope of air pollution and emissions. It would have been nice to see the news article genuinely go through the methods of research done to reach these conclusions. Another thing that I wonder is if diverting patients to DPIs and soft-mist inhalers would affect patient outcomes due to the fact that some medications may work better for some while others work better for others. I agree with the research conclusions that future medicinal prospects should include sustainability concerns, but I can't help but ponder how this may affect those who are more reliant on MDIs.
ReplyDeleteHello, Sydney. I appreciate your feedback. I agree that the article should go into the research methodologies, but this may have been difficult for a huge portion of the audience to understand. The research report makes no mention of the medical issues that patients who are prescribed MDIs face, except for children and the elderly, who may struggle to utilize them correctly. They largely discussed the cost challenges of transitioning from MDIs to DPIs or soft mist inhalers.
DeleteHi Arup! I thought this was a fascinating topic. It was really interesting how there are alternatives, like DPIs and soft-mist inhalers, but people might be hesitant to switch due to the increase in cost. Do you know what causes them to be more expensive? Also, are there significant differences in effectiveness between different inhalers? I thought the title of the new article was a clever way to give readers a comprehensible way to interpret the statistics from the research. However, it could also be seen as a potential oversimplification of the data, as there were complicated paths that led to the final numbers. Are there current legislations being worked on to provide a way to shift towards lower GHGs from inhalers without compromising financial accessibility?
ReplyDeleteHey, Kristen. Thank you for your feedback. Other solutions are more expensive due to a lack of generic procedures, complex production, increased R&D expenditures, patent difficulties, and so on. MDIs, on the other hand, have been on the market for decades and follow well-established preparation processes. Different types of inhalers, such as soft mist inhalers, require the patient's breath to produce aerosol. This may be difficult for seniors and youngsters to utilize. Various researchers and pharmaceutical companies are attempting to make modified versions of DPIs and soft mist inhalers. However, they normally file a patent for these, and the cost has risen significantly.
DeleteI loved your analysis it was super concise and easy to read. I found it interesting that a health product was contributing to the growing greenhouse gas problem. The alternative options being more expensive is problematic with respect to the everyday consumer who may not care about the environment as much as they do their own health. I also wonder whether some patients respond better with one inhaler over another. What do you think is the best solution to this problem or is this just a cost for existence. Do you think the numbers are that much higher from private insurers why would they prefer this option over others?
DeleteHello, Rahib. Thank you for giving me feedback. Other countries have implemented some solutions to this challenge. The National Health Service (NHS) in England withdrew the two most carbon-intensive inhalers from formularies, decided to make dry-powder inhalers the default therapy for patients aged 12 and up, and invested in inhaler technique teaching to reduce excess emissions. AstraZeneca is also creating a propellant that does not contribute to global warming. If successful, it is scheduled to be accessible in 2025. Sweden has likewise committed to reducing the use of MDIs to 10% of all inhalers by 2019. So, the United States can follow this model and implement something similar in this country.
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