E2A: Reducing Metered-Dose Inhalers

Is Your Inhaler Contributing to Your Respiratory Illness Exacerbations?

Educational Tools and Posters for You and Your Clinic

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Bottom Line

Metered-dose inhalers (MDIs) emit greenhouse gases that worsen climate change and, thereby, respiratory illness. For most patients, dry powder inhalers (DPIs) offer a more sustainable option without compromising care.

Your first three steps:

Ensure the diagnosis of asthma or chronic obstructive pulmonary disease (COPD) is correct and justifies an inhaler prescription.
Support patients with self-management, proper inhalers and proper technique, including action plans for illness and air pollution events.
Use the lowest carbon footprint inhaler when possible (https://www.inhalerguide.ca/).

Evidence

Environmental impact of metered-dose inhalers (MDIs)

To generate aerosol clouds for medication delivery, MDIs use various hydrofluorocarbons (HFCs) as propellants.¹
HFC-containing MDIs produce substantially higher emissions than dry powder inhalers (DPIs), with estimated greenhouse gas emissions up to 10 times greater.²
HFC emissions from MDIs account for approximately 0.03% of global greenhouse gas (GHG) emissions and are increasing by about 2% annually.² MDIs account for approximately 13% of primary care’s overall carbon footprint.³
The lifecycle emissions from one pressurized MDI (approximately 200 doses) are estimated to be equivalent to driving a car about 290 km.⁴
Around 262,000 metric tons (MTs) of GHGs could be avoided in Canada if 25% of patients on MDIs were switched to lower GHG emitting options. An additional 49,100 GHG MTs could be avoided by addressing respiratory misdiagnosis, and another 143,000 GHG MTs avoided by improving maintenance control.¹

Sustainable and safe alternatives to MDIs: Treatment efficacy and patient-centered care

Dry powder inhalers (DPIs) are available across major asthma and COPD drug classes, with many newer therapies offered primarily or exclusively as DPIs.⁵
DPIs have a lower carbon footprint per actuation (see Table 1).
When patients do want or need an MDI, some MDIs have a lower carbon footprint than others.⁵

Table 1: Estimates of carbon footprints of selected respiratory devices and treatment methods.⁵

Respiratory devices and treatment methods	Carbon footprint Per 200 actuations (Grams CO2-eq)	Carbon footprint Per dose (Grams CO2-eq)
CFC MDI	150,000-200,000	1,500-2,000
HFC-134a MDI	20,000-30,000	200-300
HFC-227ea MDI	60,000-80,000	600-800
Dry Powder Inhaler	1,500-6,000	<20
Tablets	1,500-5,000	<20

DPIs are effective for most patients regardless of disease severity and age (children >6 yrs old and adults), except in very severe exacerbations requiring nebulization or intubation.⁶[CS4.1]
Poorly controlled vs. well-controlled asthma generated 3.1-fold higher overall and 8.1-fold higher excess per capita carbon footprint, largely SABA-induced, with smaller contributions from significant healthcare resource utilization.⁷
Acute Exacerbation Control: o For acute asthma or COPD, administration of fast-acting bronchodilator via DPI is as effective or better than MDIs in clinical settings for improvements in FEV1 (review of 12 acute asthma studies, most double-blind randomized, adults and children >6 yrs old; three (3) COPD studies, one double-blind randomized, one single-blind randomized, one interventional).⁶ o The most studied DPI inhaler is Turbuhaler.⁶ (There is risk of bias as AstraZenaca funded the authors, but the search protocol is sound.)
Maintenance Therapy Control: o Asthma/COPD: patient adherence and satisfaction rates were high (81-99%) after addition of LABA DPI to asthma treatment (797 adults, 219 peds ages 4-17; open, uncontrolled, non-randomized, 3-month, multicentre study in 56 respirology clinics).⁸ o Asthma/COPD: for patients requiring ICS/LABA combo therapy, at 12 weeks after switch to DPI, well-controlled asthma increased from 7.0% to 80.3%, and severe COPD impact decreased from 13.7% to 0% (p<0.001) by standardized asthma control test (142 patients with asthma and 95 patients with COPD (78.2%, 56.8% female, mean age 51.0, 65.5 yrs, 14.0%, 45.0% current smokers, respectively).⁹ Patient health-related quality of life and satisfaction metrics also improved significantly. o Asthma: DPI inhaler (ICS/LABA) produced lower annual CO₂e per patient than usual care with MDI (108 kg vs 240 kg; p<0.001) and improved asthma control scores over 12 months (open label, primary care study (2,236 adults) with symptomatic asthma randomized to DPI or usual care with MDI).¹⁰ (GSK funded this study.) o Asthma: With new adult (age 18-80) diagnosis of asthma, at 3 months and 1 year the choice of inhaler type does not impact efficacy and safety profiles; the DPI group had significantly higher mean proportion of days covered (metric of adherence; 0.67 ± 0.23 vs. 0.62 ± 0.23; P < 0.001) and a lower risk of discontinuation (adjusted hazard ratio, 0.867; 95% CI, 0.804–0.927; P < 0.001) compared to MDI group (13,850 patients, population-based cohort on combo ICS/LABA DPI vs. MDI).¹¹
Inhaler exacerbation rates are higher with MDIs than DPIs (60% vs 22%) in adults. Incorrect inhaler use is common; while DPIs are generally easier to use, all devices require proper patient education.¹² A switch to DPI without proper education could results in an asthma exacerbation, and the carbon footprint of one (1) day of hospitalization is estimated at equivalent of six (6) months of MDI utilization.¹³
Not Everyone Can Use a DPI: MDIs with spacers may be more appropriate for very young children, patients unable to sustain adequate inhalation (~2–3 seconds), those with very severe exacerbations, or individuals with cow’s milk protein allergy (product-specific).

Why Does It Matter?

In Canada, asthma and COPD affect millions of people, with asthma alone affecting approximately 12% of the population. Metered-dose inhalers (MDIs) remain the most prescribed inhaler type. Climate change is increasing the frequency and intensity of extreme heat and air pollution events, which are linked to worsening respiratory symptoms, more frequent exacerbations, and increased respiratory-related hospital visits and admissions (and healthcare costs) and deaths.¹,²,⁴,¹⁴

At the same time, many commonly used inhalers contribute to greenhouse gas emissions. This means respiratory care is both affected by climate change and contributes to it. Through patient-centred education and shared decision-making, many patients can be safely transitioned from MDIs to dry powder inhalers (DPIs) or soft mist inhalers, helping maintain disease control while reducing treatment-related greenhouse gas emissions and supporting more sustainable healthcare.

In a global modelling study, the lowest MDI-to-DPI substitution rate (2% year-over-year) would reduce GHGs by 12% to 38% (10 yr vs. 50 yr horizon) and would save $56 billion USD to $10 trillion USD (10 yr vs. 50 yr horizon) in the social costs of carbon (the monetized value of damages associated with incremental increases in carbon emissions, including net agricultural productivity, human health, energy systems, and the environment).¹³

Climate change contributes to respiratory illness exacerbations

Climate change increases extreme weather, air pollution, and allergens like pollen—each of which raises the risk of respiratory illness exacerbations. ¹⁵, ¹⁶, ¹⁷, ¹⁸

Recent studies have found:

Global Burden of Disease (1990–2023): Extreme temperatures were linked to a 29% increase in chronic respiratory disease burden; air pollution accounted for 11% of related deaths.¹⁹
Global impact (2021): Household air pollution caused ~2.9 million deaths, including >309,000 in children under age five.²⁰
Air Pollution: Climate-related air pollution (e.g., particulate matter and ground-level ozone) is associated with more respiratory symptoms and higher respiratory morbidity (reduced lung function, more hospital visits/admission).¹⁵ Wildfire PM2.5 is associated with more respiratory morbidity per unit mass than urban PM2.5.¹⁷
o Asthma-related ED visits in children <9 yrs old rose 7.2% per 5.92 µg/m³ increase in short-term PM₂.₅ exposure.²¹
o Yellowknife, NWT: a 10 µg/m3 increase in PM2.5 from wildfire smoke was associated with an increase in asthma-related (incidence rate ratio (IRR) (95% CI): 1.11 (1.07-1.14)) and pneumonia-related ER visits (IRR (95% CI): 1.06 (1.02-1.10)), as well as an increase in COPD hospitalisations (IRR (95% CI): 1.11 (1.02-1.20).²²
o California: a 10 μg/m³ increase in wildfire PM2.5 was associated with a 1.3-10% increase in respiratory hospitalizations, compared to a 0.67-1.3% increase for non-wildfire PM2.5.23
o An increase in 1 µg/m3 in smoke PM2.5 was found to be associated with a 9.2% increase in COPD mortality among elderly people (95% CI; 8.8%-9.7%).¹⁸
o A systematic review found limited studies (5) that focus on respiratory mortality; limitations include differing measurement outcomes and lag days from smoke exposure. ¹⁷
Allergens: Pollen and allergen seasons in North America lengthened by approximately 20 days and pollen concentrations increased by 21% between 1990 and 2018.24 Pollen allergenicity is likely to increase with drought and heat stress.²⁵ Pollen concentrations could increase up to 200% by the end of the 21st century.²⁶
Extreme Weather: In a systematic review/meta-analysis, extreme weather events (floods, hurricanes, dust storms, cold spells, blizzards, ice storms, thunderstorms, typhoons, and heat waves) increased the risk of acute asthma exacerbation (with risk ratios (RR) and 95% confidence intervals (CI)) of asthma ED visits (1.25-fold; 1.14-1.37), asthma hospital admissions (1.10-fold; 1.04-1.17), asthma outpatient visits (1.19-fold; 1.06-1.34) and asthma mortality (2.10-fold; 1.35-3.27).¹⁶
Vulnerable Populations: Pediatrics patients, females, and the elderly have been documented as higher risk of respiratory morbidity from climate change pollution.¹⁶, ¹⁷, ²³

Wildfire-specific PM2.5 was found to be ∼10 times more harmful to children’s respiratory health than PM2.5 from other sources, especially for children aged 0 to 5 years.²³

Scripts

Consider one short script to use with patients who are climate aware and one script to use for patients who may be resistant to discussing climate issues.

Did you know that a standard spray inhaler, called a metered-dose inhaler (MDI), can have a carbon footprint comparable to driving a car for about 300 km — roughly the distance from Calgary to Edmonton? Over time, this can add up.

There are alternative options, such as dry powder inhalers (DPIs), that provide the same medication without the propellant gas. Many patients find them easy to use, and they have a much lower environmental impact while still effectively treating breathing conditions.

If appropriate for your care, would you be open to discussing whether a dry powder inhaler might be a good option for you?”

Since we’re renewing your inhaler today, I like to quickly check that people are still on the best option for them. Would it be okay if I reviewed inhaler options with you for a minute?

You’ve been using a metered-dose inhaler — the spray type — for a while. It works well, but there are also dry powder inhalers now that deliver the same medication.

For some people, they’re easier to use because there’s no need to coordinate pressing and inhaling. Some also like that they have less environmental impact. But they do require a slightly different breathing technique.

Would you like to know more about this?”

Deeper Dive:

40 slides presentation guiding physicians through the why, what and how of prescribing climate conscious inhalers in inpatient care.
Inhaler prescription can be optimized at multiple stages of inpatient stay: at admission, during transfers, on the wards, and at discharge. Environmental and financial benefits are explained. Concrete resources include clinical order sets, hospital formulary, discharge instructions for patients and primary care providers, multidisciplinary education campaign materials, all through examples of implementation from real cases.

https://cascadescanada.ca/resources/climate-conscious-inhaler-practices-in-inpatient-care-playbook/

50 slides presentation guiding physicians through the why, what and how of prescribing climate conscious inhalers in outpatient settings.
Inhaler prescription can be optimized at multiple levels: the need, type, technique, and disposal. Environmental and financial benefits are explained.
Resources such as detailed action plans for clinics, inhaler transition pathways for physicians, or instructional webinars can be found in the presentation. EMR search strings are also shared to help deliver impact-measured changes in the outpatient setting. This can help justify the need to invest in such a change and lessen the burden put on outpatient care teams to figure out the more logistical or nonmedical aspects of such endeavour.

https://view.publitas.com/climate-conscious-inhaler-prescribing-in-primary-care-playbook/

A clinical guide to inhalers in Canada with province-specific information on coverage, cost, and indication. Providers can see options available for SABA, ICS, ICS/LABA, ICS/LAMA/LABA filtering by diagnosis (asthma vs COPD), patient’s age, low carbon features, and type of coverage. A Quick Guide to Inhaler Switches for common inhalers is also included to help decision making and patient-centered discussions.

https://www.inhalerguide.ca/

This tool allows you to calculate greenhouse gas equivalents and translate abstract measurements and emissions numbers into concrete terms that patients can understand such as the annual emissions from cars or households. For example, instead of saying HFC from MDIs are responsible for 0.03% of all global GHG emissions each year, one could say their emissions are equivalent to 4.5 million cars on the road for a year.

https://oee.nrcan.gc.ca/corporate/statistics/neud/dpa/calculator/ghg-calculator.cfm#results

The article describes how to make patient-centered decision about inhaler prescriptions. This often results in climate conscious decision-making as current prescription practices are more tailored to mainstream clinician decision-making. Strategies to ensure effective use of inhaler device are classified in 4 categories of choosing, checking, correcting and confirming.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5989279/

Glossary

Planetary Health: “planetary health was defined as the health of human civilisations and the natural systems on which they depend.” ²⁷

Climate change: “Climate change refers to long-term shifts in temperatures and weather patterns, mainly driven by human activity (primarily due to the burning of fossil fuels like coal, oil and gas).” ²⁸

GHG emissions: “sum of seven gases that have direct effects on climate change: carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), chlorofluorocarbons (CFCs), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulphur hexafluoride (SF6) and nitrogen trifluoride (NF3).” ²⁹

MDI (metered-dose inhaler) or pMPD (pressurized MDI): “device that delivers a specific amount of medication to the lungs in the form of a short burst of aerosolized medicine that is usually self-administered by the patient via inhalation.” ³⁰

DPI (dry powder inhaler): “device that delivers medication to the lungs in the form of a dry powder.” ³¹

HFCs: hydrofluorocarbons, one of the 7 GHG.

PM2.5: particulate matter with an aerodynamic diameter less than/equal to 2.5 µm; this size of particulate matter is known to penetrate deeper into the lungs and provoke a stronger oxidative and inflammatory response, and depending on constituent molecules can dissolve into the bloodstream. ³²

Attributions

Webcopy created by Drs. Yseult Gibert, Chloe Boucher, Sonja Wicklum, Clark Svrcek and Jennifer Obeid from the Department of Family Medicine, University of Calgary Cumming School of Medicine, January 2026.

References:

¹Gagné M, Karanikas A, Green S, Gupta S. Reductions in inhaler greenhouse gas emissions by addressing care gaps in asthma and chronic obstructive pulmonary disease: an analysis. BMJ Open Respir Res. 2023;10(1):e001716. doi:10.1136/bmjresp-2023-001716.↩

² Pritchard JN. The climate is changing for metered-dose inhalers and action is needed. Drug Des Devel Ther. 2020;14:3043-3055. doi:10.2147/DDDT.S262141. ↩

³ Syed DH, Syed DL, Sornalingam DS, Cooper DM. Achieving net-zero carbon care in general practice. InnovAiT. 2023;16(12):618-623. doi:10.1177/17557380231203910. ↩

⁴ Fidler L, Green S, Wintemute K. Pressurized metered-dose inhalers and their impact on climate change. CMAJ. 2022;194(12):E460. doi:10.1503/cmaj.211747. ↩

⁵ Medical and Chemical Technical Options Committee. 2018 assessment report: Montreal Protocol on substances that deplete the ozone layer. Published 2018. Accessed February 13, 2026. Link. ↩

⁶ Selroos O, Borgström L, Ingelf J. Use of dry powder inhalers in acute exacerbations of asthma and COPD. Ther Adv Respir Dis. 2009;3(2):81-91. doi:10.1177/1753465809103737. ↩

⁷ Wilkinson AJK et al. Greenhouse gas emissions associated with suboptimal asthma care in the UK: the SABINA CARBON study. Thorax. 2024;79(5):412–21. doi:10.1136/thorax-2023-220259. ↩

⁸ Gálffy G et al. Inhaler competence and patient satisfaction with Easyhaler. Drugs R D. 2013;13(3):215-22. doi:10.1007/s40268-013-0027-3. ↩

⁹ Gálffy G et al. Clinical effectiveness after switch to Easyhaler. Thorax. 2019;74:A212-A213. ↩

¹⁰ Woodcock A et al. Effects of switching inhalers on emissions and asthma control. Thorax. 2022;77(12):1187-1192. doi:10.1136/thoraxjnl-2021-218088. ↩

¹¹ Park HS et al. Comparative analysis of ICS/LABA combinations. Respir Res. 2025;26(1):12. doi:10.1186/s12931-024-03084-7. ↩

¹² Ramadan WH, Sarkis AT. Patterns of inhaler use. Chronic Respiratory Disease. 2017;14(3):309-320. doi:10.1177/1479972316687209. ↩

¹³ Kponee-Shovein K et al. Impact of inhaler choice on carbon footprint. Journal of Medical Economics. 2022;25(1):940–953. ↩

¹⁴ Public Health Agency of Canada. Asthma and COPD in Canada, 2018. Link. ↩

¹⁵ Xu Z et al. Climate change and children's health. Int J Environ Res Public Health. 2012;9(9):3298-316. ↩

¹⁶ Makrufardi F et al. Extreme weather and asthma. Eur Respir Rev. 2023;32(168):230019. ↩

¹⁷ Jiao A et al. Wildfire particulate matter and respiratory outcomes. Sci Total Environ. 2024;907:168134. ↩

¹⁸ Xu K et al. Long-term exposure to smoke PM2.5 and COPD mortality. Environ Int. 2025;199:109513. ↩

¹⁹ Global Burden of Disease Collaborative Network. GBD 2023 results. Link. ↩

²⁰ World Health Organization. Household air pollution and health. 2024. Link. ↩

²¹ Weichenthal SA et al. Fine particulate matter and respiratory illness. Am J Respir Crit Care Med. 2016;194(5):577-586. ↩

²² Howard C et al. Summer of Smoke study. BMJ Open. 2021;11:e037029. ↩

²³ Aguilera R et al. Wildfire smoke impacts respiratory health. Nat Commun. 2021;12:1493. ↩

²⁴ Anderegg WRL et al. Climate change and pollen seasons. PNAS. 2021;118(7):e2013284118. ↩

²⁵ El Kelish A et al. Ragweed pollen allergenicity. BMC Plant Biol. 2014;14:176. ↩

²⁶ Zhang Y, Steiner AL. Climate-driven pollen changes. Nat Commun. 2022;13:1234. ↩

²⁷ Whitmee S et al. The Lancet Commission on planetary health. Lancet. 2015;386:1973-2028. ↩

²⁸ United Nations. What is climate change? Link. ↩

²⁹ OECD. Greenhouse gases data. Link. ↩

³⁰ Metered-dose inhaler. Wikipedia. Link. ↩

³¹ Dry powder inhaler. Wikipedia. Link. ↩

³² Ishihara Y et al. Fine particulate matter and CNS impact. Antioxidants. 2025;14(6):730. ↩