Approaches to reduce inhaler-related greenhouse gas emissions

Pressurized metered-dose inhalers (MDIs) currently rely on hydrofluorocarbon (HFC) propellants, which are potent greenhouse gases (GHGs). In contrast, dry powder inhalers (DPIs) and soft mist inhalers (SMIs) have an overall carbon footprint that is about 10 times lower than that of MDIs. The use of DPIs and newer MDIs using non-HFC propellants presents opportunities for significant reductions in health system GHG emissions. The Canadian Thoracic Society (CTS) recognizes its role in addressing the lung health impacts of climate change, and has issued a position statement on reducing inhaler-related GHG emissions. The CTS has also published a CTS Choosing Wisely statement related to this issue. The CTS outlines several approaches to reduce inhaler-related GHG emissions: Improve use of diagnostic testing. Objective testing is infrequently used to diagnose respiratory diseases, leading to many patients being misdiagnosed with airways disease. For example, studies suggest that 31%–44% of patients diagnosed with COPD in primary care do not actually have the disease. Improving objective diagnosis of airways disease may significantly reduce unnecessary inhaler use and corresponding GHG emissions. Improve adherence to guideline-directed care. More than 50% of patients with asthma and COPD have inadequate disease control due to suboptimal controller inhaler regimens, resulting in excessive use of short-acting beta-agonist (SABA) reliever inhalers. Overuse of SABAs (> 2 canisters/year) is a major contributor to inhaler-related GHGs, since SABAs are overwhelmingly prescribed as MDIs. Improving adherence to guideline-based assessment of disease control and corresponding therapeutic escalation could significantly reduce the carbon footprint associated with asthma and COPD, through reduction in rescue MDI use and by averting the need for exacerbation care. Ensure appropriate MDI technique. Inhalers (particularly MDIs) are used incorrectly 12%–71% of the time. Misuse of MDIs is particularly common in older adults and children. Ensuring proper inhaler technique and encouraging the use of a spacer with an MDI can lead to greater drug delivery, resulting in improved disease control, decreased SABA overuse, fewer exacerbations and reduced GHG emissions. Prioritize DPIs over MDIs. When starting a new controller or rescue medication, healthcare providers can prioritize DPIs over MDIs. Patients currently receiving an MDI can often be switched to a DPI. In one study, changing an MDI to a DPI halved the carbon footprint among people with asthma without significantly affecting their asthma control. When an MDI is needed, healthcare providers can select one that uses a lower GHG propellant (HFC-134a rather than HFC-227ea) and/or “low volume” HFC, which have a smaller metered valve, reducing emissions. Several factors must be considered when selecting an inhaler device (patient preference; impact of inhaler device on adherence; inhalation technique and patient ability; inspiratory flow rate/pressure required for adequate medication delivery and patient ability; patient age; cost for patient and/or public healthcare system; side effect profile; and environmental footprint). Educate patients about inhaler disposal options. Inhaler disposal through incineration reduces GHGs from MDIs. Incineration thermally degrades HFC chemicals, resulting in lower global warming potential byproducts. Recycling also has the potential to reduce GHG emissions through the recovery of the propellant during the disposal phase. Patients should be educated to return their inhalers to their pharmacy for proper disposal. The position statement includes a table summarizing the carbon footprint of various types of inhalers, along with factors that influence inhaler choice. Strategies for implementing various approaches to reduce inhaler-related greenhouse gas emissions are also presented. The statement acknowledges that newer propellants with much lower global warming potential than current HFCs are approaching market release, which will shift the balance of the environmental harms between MDIs and DPIs. CTS Choosing Wisely statement on MDIs Don’t prescribe greenhouse gas-intensive MDIs for asthma and/or COPD where an alternative inhaler with a lower carbon footprint (e.g., DPI, SMI, MDI with a low GHG potential propellant) containing medications with comparable efficacy is available, and where the patient has demonstrated adequate technique and patient preference has been considered. Reference 1. Gupta S, Couillard S, Digby G, et al. Canadian Thoracic Society position statement on climate change and choice of inhalers for patients with respiratory disease. Can J Respir Crit Care Sleep Med 2023; published online October 11, 2023. (accessed November 21, 2023).

Approaches to reduce inhaler-related greenhouse gas emissions

Register for free access or login.

Related Topics