Measuring the impact of metered-dose inhalers in British Columbia

Updated on August 9, 2023 (Originally posted on August 4, 2023) The Tablet

A BCMJ paper published in May 2023 examined prescribing patterns using PharmaNet data and calculated the climate impact of inhalers in the Fraser Health region

By Kevin Liang, MD, CCFP; Darryl Quantz, MFPH, MPH, MSc

The greenhouse gas emissions of the Canadian healthcare system is among the highest in the world, and pressurised metered-dose inhalers (pMDIs) contribute significantly to this carbon footprint. Because pMDIs use liquefied gases called hydrofluoroalkanes (HFAs) as propellants to deliver medication to the lungs, they release potent greenhouse gases into the atmosphere on actuation and if disposed of improperly.

A recent BCMJ paper published in May 2023 examined prescribing patterns using PharmaNet data and calculated the climate impact of inhalers in the Fraser Health region— the most populous health region in British Columbia. Using the available data, the researchers also estimated the prevalence of short-acting ß2-agonist overuse in patients with asthma—a powerful indicator of poor asthma control and a significant source of emissions.

Figures 1 and 2 inhalers

The results show that from 2016 to 2021, more than 3.56 million inhalers were prescribed for Fraser Health region residents; an average of 394,094 pressurised metered-dose inhalers and 199,536 dry powder inhalers/soft mist inhalers were dispensed per year.

The resulting carbon footprint of inhalers was 8,478 tCO2e per year, and pressurised metered-dose inhalers accounted for more than 98 per cent of the footprint. To put this in context, the annual average measured emissions from the Fraser Health region, which includes 174 buildings with 13 acute care hospitals in 2021, over the same six-year period was 38,951 tCO2e. Patients are prescribed a higher proportion of pMDIs compared to low-carbon alternatives that have similar efficacy. Switching to dry powder inhalers (DPIs) when clinically appropriate can significantly reduce emissions.

The article highlights the clinical concerns associated with pMDIs, such as suboptimal inhaler technique and difficulties in determining when the inhaler is empty. DPIs and soft mist inhalers offer improved medication deposition and once-a-day dosing, which can enhance adherence. The study also emphasises the prevalence of short-acting ß2-agonist overuse, which is associated with poor asthma control and increased exacerbation risks. 

How community pharmacists can help

By Valeria Stoynova, MDCM, FRCPC, MHPE; Celia L. Culley, BSP, ACPR, PharmD

Climate change is affecting the health of British Columbians as part of a global trend towards adverse health outcomes.1 Every year, climate-related events such as wildfires, heat domes, and floods cause morbidity and mortality, disproportionately affecting our most vulnerable populations.1 This year is no exception; the 2023 wildfire season includes the largest fire in B.C.’s history, covering an area greater than Prince Edward Island and leading to evacuations and disruptions in healthcare delivery.2

Paradoxically, many healthcare interventions needed to keep our patients healthy — including medications — can exacerbate the climate crisis by creating outsized carbon emissions. We know that the Canadian healthcare system accounts for 4.6 per cent of the national greenhouse gas (GHG) emissions, a quarter of which are related to prescription and non-prescription medications — inhalers among them.3 In their recent paper, Liang et al. elegantly capture the scope of inhaler-related carbon footprint in the Fraser Valley through a retrospective review of community inhaler dispensing.4 Their alarming findings highlight the medication-related practices that are contributing to our GHG emissions and model potential strategies to decrease this footprint at the prescriber level. This begs the question: how can we, as healthcare providers, do our part to provide high quality patient care while simultaneously minimizing our environmental impact?

Pharmacists are trusted voices in the patient’s care team. As accessible healthcare professionals with expertise in medication management, pharmaceutical supply chains, and drug shortages, pharmacists and pharmacy technicians are well positioned to positively influence healthcare delivery. Healthcare organizations are increasingly recognizing the key contributions of pharmacy professionals in providing climate conscious healthcare with calls to action published in major pharmacy journals,5,6 pharmacy-specific Environmental Sustainability Taskforces,7 and national step-by-step guides on low-carbon sustainable pharmacy practice.8


While the potential contributions are manifold, we propose here five small steps with a big impact you can take in your community pharmacy practice today to mitigate the climate impact of therapy, while continuing to provide high quality, patient-centered care.

1. Educate yourself on climate impacts of inhalers.

Among the many excellent Canadian-specific resources, we recommend reviewing the two inhaler Playbooks from the knowledge mobilization network CASCADES (Creating a Sustainable Canadian Healthcare System in a Climate Crisis). These include literature summaries which highlight the issue in a Canadian context and include provider- and patient-facing resources and can be found at

2. Recommend, source, and dispense lower carbon and low volume HFA MDI devices where feasible.

Liang et al. highlighted that the vast majority of the inhaler-related carbon footprint in the Fraser Valley is related to MDIs.4 However, not all MDIs are made equal. There is substantial variability in the carbon footprint among inhalers, even within the same device type and pharmacologic category.

Some MDIs use ethanol or oleic acid as an HFA-sparing agent, which markedly lowers their carbon footprint.9,10,11 These “low-volume” HFA inhalers have the same device type, the same active ingredient, the same number of doses, the same indications, contraindications, and inhaler technique; the main measurable difference is the carbon footprint which can be cut by two-thirds by selecting low-volume HFA devices. As an example, a high-volume HFA rescue inhaler has the carbon footprint equivalent of driving up to 112.6 km in a standard gasoline-powered vehicle whereas the low-volume inhaler is equivalent to 38.8 km.11

Knowing these differences and carefully weighing carbon footprint as part of the decision-making process when choosing which inhaler to source for your pharmacy can make a significant difference.

Pharmaceutical companies are currently developing lower-carbon propellants such as HFA-1234ze12 and HFA-152a10 that will further lower MDI carbon footprint further, which are expected to hit the Canadian market in another five to seven years.

3. Continue to regularly review patients’ inhaler technique.

An inhaler is only as effective as the technique with which it is used. We know that the majority of patients have at least one critical handling error when using their inhaler.13 We also know that inhaler technique declines over time; even patients who have been on inhalers for many years and feel confident with their technique can develop critical handling errors which can decrease drug delivery and effectiveness.14

Pharmacists are well positioned to review inhaler technique with patients on a regular basis.16 Online videos can be a useful adjunct to in-person teaching, and we recommend the high quality, brief and patient-centered videos that can be found on the Canadian Lung Association website. Inhaler teaching best practices include observing the patient using their inhaler, then providing targeted feedback on their technique.14-16

Continue to counsel patients that all MDIs should always be used with a valved chamber holding device (spacer device), which greatly increases drug delivery to the lung tissue.16

4. Identify patients with asthma and COPD who may benefit from optimization of maintenance therapy.

Particularly in the current context where primary care providers are a scarce resource in B.C., the community pharmacist is regularly the healthcare provider with the most exposure and continuity of care with a patient. 

We know that rescue inhaler use is a marker of disease control in patients with asthma.17 We also know that salbutamol refills can be used as a surrogate marker for disease control, with poorly controlled asthma defined as the use of two or more rescue inhalers per year. Community pharmacists can readily identify patients with high frequency of rescue inhaler refills and review and optimize maintenance therapies with patients if already prescribed. If necessary, pharmacists can contact the prescriber with medication recommendations to optimize disease control, or counsel the patient to seek care as appropriate.

Identifying such patients can trigger a review by their prescriber to reassess inhaler regimens, technique, investigate alternate diagnoses which could be missed (e.g. heart failure, pneumonia), or screen for comorbid conditions that can markedly worsen asthma control (e.g. acid reflux, allergic rhinitis). By promoting better asthma maintenance, we further decrease the carbon footprint of therapy by reducing the need for carbon-intensive rescue MDIs and reducing high-carbon components of care such as ER visits and hospital admissions.19 Most importantly, better disease maintenance improves the health and quality of life of our patients.

5. Educate about and ensure appropriate inhaler disposal.

The majority of MDIs in B.C. have no dose counters, meaning there is no way to accurately quantify how many doses are left within the inhaler at the time of disposal. Although the “float test” has been taught historically, it is neither sensitive nor specific, and is not recommended.20 The lack of dose counters can lead to patients underestimating how many doses are left in their device, which in turn leads to the premature disposal of inhalers while there is still active ingredient and propellant remaining.21

We know that up to a third of the carbon footprint of MDIs comes at the end-of-life phase once the inhaler is ready to be discarded.22 For safe disposal, the propellant needs to be incinerated at high temperatures to neutralize the remaining propellant.22

The Health Products Stewardship Association (HPSA) is a national organization operating in BC whose mission is to promote environmentally safe medication disposal. We encourage you to see if your pharmacy is registered — or learn more about registration to their free post-consumer medication takeback programs at

Pharmacy professionals play a central role in providing climate-conscious care. High yield actions include prioritizing low-carbon inhalers when feasible, reviewing inhaler technique, optimizing patients’ disease control, and safe inhaler disposal. Although the climate crisis is creating new challenges for the delivery of healthcare, we can take immediate action to protect our patients by mitigating some of the climate impact while continuing to provide high quality, patient-centered care. 

  1. The Lancet Countdown on Health and Climate Change – Policy brief for Canada. Published October 2021. Accessed July 7, 2023 from
  2. Kulkarni A, What Happens After The Donnie Creek Wildfire, now larger than P.E.I., stops burning? CBC News. July 3, 3023. Accessed July 7, 2023 from
  3. Eckelman MJ, Sherman JD, MacNeill AJ. Life cycle environmental emissions and health damages from the Canadian healthcare system: An economic-environmental- epidemiological analysis. PLoS Med. 2018;15(7): e1002623. pmed.1002623 
  4. Liang KE, Yao JA, Hui P, Quantz D. Climate impact of inhaler therapy in the Fraser Health Region 2016-2021. BCMJ. 2023;65(4):122-127.
  5. Beechinor RJ,Overberg A, Brown CS, Cummins S, Mordino J. Climate change is here: What will the profession of pharmacy do about it?. AJHP. 2022;79(16):1393-1396.
  6. Roy C. The pharmacist’s role in climate change: a call to action. CPJ. 2021;154(2).
  7. Canadian Society of Hospital Pharmacists. Call for expression of interest - sustainability task force. Published February 7th, 2023. Retrieved July 7th, 2023 from
  8. CASCADES. Climate Resilient, Low Carbon Sustainable Pharmacy. Retrieved July 7, 2023 from CC BY-NC-SA 4.0)”
  9. Myrdal PB, Sheth P, Stein SW. Advances in metered dose inhaler technology: Formulation Development. AAPS PharmSciTech. 2014;15(2):434-455. doi: 10.1208/s12249-013-0063-x
  10. Jeswani HK, Azapagic A. Life cycle environmental impacts of inhalers. J Clean Prod. 2019;237:117733

11.   Stoynova V, Culley C. Detailed Inhaler Carbon Footprint Chart. Version February 2, 2023. Retrieved July 7, 2023 from

  1. Hargreaves C, Budgen N, Whiting A et al. A new medical propellant HFO-1234ze: reducing the environmental impact of inhale medicines. Thorax. 2022;77(1).
  2. Usmani OS, Lavorini F, Marshall J et al. Critical inhaler errors in asthma and COPD: a systematic review of impact on health outcomes. 2018;19(10)

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