asthma: HFA inhalers are really environmentally toxic

 I heard an impressive segment on NPR on May 6 about the rather extensive potential environmental damage done by asthma/COPD inhalers that use a propellant (the boot-shaped inhalers): https://www.npr.org/sections/health-shots/2024/05/06/1248504466/could-better-asthma-inhalers-help-patients-and-the-planet-too . This segment highlighted Dr. Miguel Divo, a pulmonologist in Boston, who is a strong advocate for using dry powder inhalers (DPIs) instead of the environmentally toxic ones using a propellant gas, now hydrofluoroalkanes (HFAs). 

Details:

From a 2021 report by the US environmental protection agency (https://www.epa.gov/sites/default/files/2021-03/documents/epa-hq-oar-2021-0044-0002_attachment_1-mdis.pdf ):

    -- the pharmaceutical industry initially used chlorofluorocarbons (CFCs) as the propellant in metered dose inhalers (MDIs), though these were phased out and fully replaced by hydrofluoroalkanes (HFAs) by 2014

        --  CFCs not only deplete the ozone layer in the atmosphere but also are potent chemicals causing global warming

    -- each puff from one of the HFA inhalers releases hydrofluorocarbon gas that is 1430 to 3000 times as powerful as carbon dioxide as a greenhouse gas (https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter_07_Supplementary_Material.pdf )

    -- by 2020, the EPA calculated that 1491 metric tons of HFC (hydrofluorocarbon) propellant was contained in MDIs sold just in the United States, with projected 1595 metric tons by 2025; these inhalers were used by the 19.2 million adults and 5.5 million children with asthma and 12.8 million adults with COPD, per the CDC statistics in 2018.

        -- The amount of gas released into the atmosphere “is the equivalent of driving half a million gas-powered cars for year”

    -- 88% of the market in 2020 involved HFAs for a total of 144 million HFC MDIs sold in the United States; 12% used DPIs (dry powder inhalers)

 -- A 2022 report in the European Respiratory Journal (see asthma inhalers environment effect EurRespJ2022 in dropbox, or DOI: 10.1183/13993003.02106-2021) made the following comments:

    -- most of the pressurized metered dose inhalers involve hydrofluorocarbons that are potent greenhouse gases

    -- they note that based on one month’s treatment, the DPI of formoterol/beclometasone had a carbon footprint of 0.916 kg versus pressurized MDIs leading to the equivalent of 11.330 kg of carbon dioxide (i.e. one month’s pressurized MDI use was approximately equivalent to a year of DPI use). This analysis includes the energy and water consumption used during the manufacture and the device packaging, which had the biggest impacts on the carbon footprint

    -- the clinical comparison between MDIs and DPIs is a bit complex given the large differences in inhalation techniques for these two types of inhalers. Many patients have difficulty with the coordination required for correct MDI use and find it easier to use DPI’s, which are triggered by their own inhalation; patients with limited lung function (very young, very old, or those with an exacerbation of their asthma/COPD) however may not achieve the inspiratory flow rate needed to get the full dose from DPIs. Overall, the authors note that the majority of patients are able to generate a sufficient inspiratory flow to use low resistance DPIs appropriately

    -- another issue, of course, is that the relative costs of DPIs is higher than MDIs, making the change particularly difficult in low-income countries. In high-income, countries the relevant costs of these therapies vary greatly, depending on market factors (e.g., DPIs are much more expensive in the United States and Puerto Rico but significantly cheaper in the UK, Canada, and Australia)

    -- also, there are some HFC propellants that are less environmentally toxic than others: HFC-152a is much less toxic than HFC-227ea and HFC-234a (these latter ones account for >90% of the overall product carbon footprint). Some manufacturers are looking to change the propellant and the FDA has is spending about $6 million in a study about the challenges of developing inhalers with a smaller carbon footprint

    -- and, of course, there is the concern that any change in the production of these new inhalers will lead to large increases in their cost (as happened in past with the switch from CFCs to HFCs), since these become new products that will have new long-lasting patents allowing the drug companies to increase costs lots,  given the unavailability of lower-cost generics

 

 From GoodRxHealth, these are the dry powder inhalers available: they look like discs instead of the old boot-shaped ones:

 

-- here is a link to an environmentally-friendly approach to inhalers, a 1-pager from the Canadian Medical Association Journal that delineates the issues of pressurized MDIs and their impact on climate change:  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8967439

So, 

-- one of the issues here is that these boot-shaped HFA inhalers are remarkably environmentally toxic. And to the extent that they add to global warming, they are part of the positive feedback cycle whereby climate change leads to the vicious cycle of more wildfires, more air pollution, and more difficulty for those who have asthma or COPD, requiring even more inhaler use

-- and, as we know, there is the overall positive feedback loop for climate change: a warming climate leads to accelerated warming, whether by unfreezing "perma"frost and releasing huge amounts of carbon dioxide stored there, or by melting white-colored and reflective ice and snow leading to increased solar radiation absorbed by the darker surface, or by changing plants to be less able to absorb carbon dioxide, or by warmer temperatures leading to more water vapor in the air from evaporation and more heat trapped by the water vapor, or......

-- which all means that we need to act globally soon and hard to decrease or more likely stabilize the already-apparent effects of climate change (as last week’s real-feel of 104 degrees in Boston attests to). And HFA inhalers are a pretty easily correctable part of the problem

 

 

geoff

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