Breaking the climate-lung health cycle: Rethinking the metered-dose inhaler

With each passing summer, it has become painfully clear that wildfires are a recurring phenomenon that is here to stay. Just as winter is hockey season in Canada, summer has become fire season.The most grave health risk from wildfires is posed by breathing in tiny particles called PM 2.5 (particulate matter that is 2.5 microns or smaller) that are suspended in wildfire smoke. Estimates suggest that particulate matter exposure from spending a half day outside in some of the hardest hit parts of the country this summer was comparable to the exposure from smoking a half pack of cigarettes.The lungs are the great human air filter—filtering more than 10 000 liters of air per day - which means they are the first point of entry for this pollution. Accordingly, although even healthy people can be affected (especially if exercising outdoors), the smoke poses a greater risk to those with chronic diseases, and particularly those with lung disease.Studies show that wildfires drive increased emergency room visits for flare-ups of asthma and chronic obstructive pulmonary disease (COPD), both among the most common chronic diseases in Canada. Much like the patient with arthritis whose joints start aching when a storm is on the horizon, my patients start experiencing cough, tightness, wheeze, and shortness of breath as the smoke approaches. When this happens, they turn to their rescue inhaler for immediate relief—most commonly in the form of a metered dose inhaler (MDI). What most users don’t know is that the propellant that generates the medication plume from an MDI is a potent greenhouse gas comprised of hydrofluorocarbons, released with each puff. Estimates suggest that a single canister of the most commonly used metered-dose inhaler releases the carbon equivalent of 137 km. car journey.Greenhouse gases cause global warming, which is the root cause of the wildfire crisis. Accordingly, patients find themselves in an awkward circular conundrum whereby each puff of the very rescue inhaler that they desperately require when they are exposed to wildfire smoke contributes to climate change and hastens the next catastrophic wildfire event.But there are solutions. Dry powder inhalers are available for nearly every class of medication dispensed through MDIs, and have a carbon footprint that is 10-fold lower. Although they are prescribed less often, multiple studies show that these medications are just as safe and effective, and can be used interchangeably with metered-dose inhalers in the vast majority of patients, when accompanied by proper education around technique (with exceptions including children under the age of 6 and older adults with muscle weakness). Accordingly, the Canadian Thoracic Society encourages prescribers to prioritize dry powder inhalers over equivalent MDIs, after considering factors including safety, cost, patient technique, ability and preference. Given that 800 million MDIs are prescribed annually around the world, a switch to dry powder inhalers represents an important opportunity for carbon mitigation. Notably, guidelines also emphasize the importance of routine asthma and COPD care, including objective diagnosis, evaluating disease burden by guideline criteria, optimizing day-to-day “controller” therapies, and empowering patients to self-manage flare-ups, all of which not only lead to better patient outcomes but also to a lower carbon footprint by reducing symptom burden and corresponding rescue inhaler use, as well as urgent care use.Our recent survey of inhaler users across Canada demonstrated that most (84%) were concerned about climate change, but only 20% knew that their metered-dose inhaler released greenhouse gases. When educated on the topic, 92% expressed interest in switching to a lower carbon footprint device, if advised so by their physician. However, healthcare providers need practical bedside tools that enable them to efficiently review the pros and cons of different inhaler devices with their patients, to reach a shared treatment decision. This has led to the recent development of simple “conversation aids” comparing different devices within each medication class on facets such as cost, dosing, and carbon footprint, for use at the point-of-care. These tools, now endorsed and used by 14 different national organizations (spanning respirologists, family physicians, allergists, nurses, respiratory therapists, cardiopulmonary technologists, pharmacists, and patients), are available at: https://lungtoolkit.com/eco.If you are among the tens of thousands of healthcare providers who prescribe, dispense, and/or educate around inhalers, then consider encouraging your patient to select a lower carbon device when initiating therapy. If appropriate, also consider starting a conversation with your patient on existing MDI therapy about switching to a lower-carbon device (either a dry powder inhaler, or in some cases, a lower carbon MDI alternative). This will not be right for all patients, but many will feel empowered by this small but very personal opportunity for action. In fact, some may lament a missed opportunity to reduce their carbon footprint if indeed they are not offered this choice. The hope is that with the help of these conversation aids, healthcare providers might add shared decision making around inhaler selection to the many day-to-day choices that many of us are already making to reduce our carbon footprint.Though small, when multiplied, these simple acts may yet help prevent tomorrow’s fires.Dr. Samir Gupta is an associate professor in the University of Toronto department of medicine and the division of respirology past chair, Canadian Respiratory Guidelines Committee, Canadian Thoracic Society. Dr. Gupta has received a number of peer-reviewed grants for this work, and invented a computerized decision support system for respiratory care which incorporates these tools.

Breaking the climate-lung health cycle: Rethinking the metered-dose inhaler

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