MDI asthma inhalers come under scrutiny over heavy carbon cost

Preventing life-threatening asthma attacks has become a lifelong job for Fred Langlois. Now in his 40s, Langlois vigilantly avoids triggers such as pollen and respiratory viruses and uses at least three different inhalers every day.

Inhalers, a lifesaving treatment for people with asthma and other respiratory diseases, send medications directly to the lungs, targeting affected airways and giving patients often-instant relief. However, the medium through which the medications travel recently has come under increased scrutiny. The familiar blue and orange puffers fall under a class of medication called metered-dose inhalers (MDIs). To work, MDIs use a pressurized propellant to carry medication to the airways.

“The propellants used in MDIs are approximately 1,000 times as powerful of a greenhouse gas as carbon dioxide,” says Samantha Green, a family physician and leader University of Toronto’s Sustainable Inhaler Initiative, adding that small amounts of the propellants use in an inhaler can have an “outsized” climate footprint. In fact, “the carbon footprint from one typical MDI is estimated to be around the equivalent of driving a car for 290 kilometres,” notes Green.

Low carbon alternatives exist. Dry powder inhalers (DPIs) do not require any propellant. Instead, patients use the force of their lungs to inhale the medication. Meanwhile, soft-mist inhalers (SMIs) have a spring mechanism to release medication in a fine mist. The carbon footprint of DPIs and SMIs are entirely from their manufacturing and disposal process that are magnitudes less than MDIs.

There is a growing call for patients to toward dry powder alternatives.

In North America, MDIs are the predominant form of inhalers prescribed. In response, there is a growing call for patients to switch away from MDIs and toward the low-carbon alternatives as more articles emerge detailing the environmental harms of MDIs compared to DPIs and SMIs. But not everyone with asthma or needing inhalers agrees with this message.

“I felt singled out for needing a life-saving medication,” recalls Alyssa Scanga, a 20-year-old student and climate organizer based in Peterborough, Ont., when she read an article from CBC detailing MDIs’ footprint.

Alyssa has lifelong asthma but over the past three years, she has needed increasing doses of her two inhalers due to air pollutants from the prolonged wildfire season and heatwaves. Both inhalers are MDIs.

Switching inhaler types has presented barriers for her; in part, only MDIs are consistently covered by her insurance drug plan. In addition to cost, Alyssa also has been solely prescribed MDIs by her doctor and fears a different inhaler may not work effectively during life-threatening asthma exacerbations.

Indeed, DPIs and MDIs do not work for everyone. Patients must have the necessary manual dexterity and, for DPIs specifically, generate sufficient inspiratory force. As a result, Green prescribes MDIs with a spacer (a chamber that holds the spray from the inhaler as it is slowly inhaled) for infants, pre-schoolers, elderly individuals and those with cognitive impairment.

Alyssa feels unfairly burdened by an increased focus on the carbon footprint of her inhalers. She says it is unnecessary as there are greater sources of emissions, and it creates sentiments of “eco-ableism” – defined as a failure to recognize that many climate actions make life difficult for disabled people. 

“Cutting down on my MDI use to fight climate change could mean sacrificing my own health,” she says.

Green recognizes those concerns and says “every barrier must be addressed in a shared decision-making process with patients” when switching away from MDIs. But, adds Green, more importantly, a discussion of MDIs’ carbon footprint is not about asking patients to jeopardize their asthma control for carbon savings. Instead, it is an “opportunity to improve patient care.”.

Every time Green renews an inhaler prescription, she checks that the patient has the correct diagnosis. Since up to a third of patients in Canada are misdiagnosed with asthma, using inhalers for the incorrect indication can cause undue harm.

As well, there are respiratory benefits to the low-carbon inhalers. Studies have shown that patients make fewer errors using DPIs than MDIs, indicating that substantial carbon savings can be achieved while concurrently improving asthma control.

The benefits ring true for Fred Langlois.  

“MDIs can be quite tricky to use,” he says. “They require a slow, steady breath, but with DPIs, I can time my breath.”

Andrea MacNeill, a surgical oncologist at Vancouver General Hospital and a global leader in health-care sustainability, says it is the responsibility of everyone in health care to make low-carbon options the “best option for patients.”

‘Actions that improve quality of care will invariably reduce environmental impact.’

MacNeil, who launched Canada’s first Planetary Health Lab, an interdisciplinary initiative aimed at tackling health care’s growing environmental impact, notes that every switch to a lower carbon alternative must first consider and address “the differences in cost, access and patient experience.”

But decarbonizing health care goes beyond tackling the carbon footprint of individual medical products. McNeill’s framework involves completely reorienting “our focus in medicine from simply treating disease to prevention and promoting health and wellness.”

Within health care, “actions that improve quality of care will invariably reduce environmental impact,” emphasizes MacNeill.

All medical interventions carry at least some carbon cost. Every year, health care in Canada generates 33 million tonnes of carbon dioxide equivalents, or 4.6 per cent of national emissions. A dedicated focus on these figures and the aim to drive it to zero can feel like a threat to the health of individual patients like Alyssa and Fred.

Instead, decarbonizing health care is a movement toward improving the health and wellbeing of patients by rethinking our model of care. In this re-envisioned system, decarbonizing health care means ensuring Alyssa and Fred have the needed medications to prevent asthma exacerbations. And when they need inhalers, the low-carbon options are accessible and affordable since they often provide the best care.

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Kevin Liang


Kevin Liang is a resident physician in the Department of Family and Community Medicine at the University of British Columbia. 

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