ABSTRACT

Background The scientific evidence indicates little or no difference in the effectiveness or cost of using of metered-dose inhalers (MDIs) versus nebulization to treat acute asthma in the emergency department (ED). However, the use of MDIs raises questions of environmental impact. The objective of this study was to compare the carbon footprint of salbutamol administered by MDI versus nebulization.

Methods Applying a life cycle assessment methodology, we quantified the resources extracted and pollutants emitted by each therapeutic option, from the factory production of medication and equipment to disposal by incineration. Each piece of inventory data was then translated into CO2-equivalent emissions (CO2eq) using the IPCC2021/GWP100 method. Results were estimated for the administration of 1 and 3 treatments of 800 µg of salbutamol by MDI and 5 mg by nebulization (standard doses for adults and children ≥ 24 kg) and compared to the use of a subcompact car.

Results One and three ED-administered treatments with salbutamol emit respectively 1.9 and 4.0 kg of CO2eq via MDI versus 0.9 and 1.0 kg via nebulization, which corresponds to 5.5 km and 11.6 km and to 2.7 km and 2.8 km traveled in a subcompact car. Each series of 8 inhalations from an MDI releases 1.1 kg of CO2eq due to emission of the hydrofluoroalkane propellent.

Interpretation Considering the absence or minimal difference in clinical effectiveness, this study suggests that nebulization may be a more eco-efficient administration route than MDIs in the emergency treatment of asthma.

Study question What is the ecological footprint of metered-dose inhalers compared to nebulization for administering salbutamol when treating a patient with acute asthma in the emergency department?

Results Nebulization was found to have half the carbon footprint of 1 MDI administration and one quarter of 3 MDI administrations.

Interpretation Implementing low-emission treatment protocols for acute asthma should be one of many avenues to explore to achieve net-zero greenhouse gas emissions in healthcare services.

Competing Interest Statement

The authors have declared no competing interest.

Funding Statement

This study was funded by a grant from the Association des specialistes en medecine urgence du Quebec.

Author Declarations

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

Footnotes

Ethics approval : Not applicable due to the study design (life cycle assessment).

Presentation : This work was presented on June 4th at the 2024 Canadian Association of Emergency Physicians Conference.

Financial support: This study was funded by a grant from the “Association des spécialistes en médecine d’urgence du Québec”.

Conflict of interest disclosure: The authors have no conflict of interest to disclose.

Data Availability

All data produced in the present study are available upon reasonable request to the authors.

AbbreviationsEDemergency departmentCO2eqCO2 equivalentsMDImetered-dose inhalersCOPDchronic obstructive pulmonary diseaseHFAhydrofluoroalkaneDALYdisability-adjusted life-yearMJmegajoulePDF m2 yearpotentially disappeared fraction of species over square meter yearsIPCC2021 GWP100Intergovernmental Panel on Climate Change for 2021 – Global Warming Potential for 100-year periodDPIdry powder inhaler