How to reduce carbon footprints in asthma

Extract

Climate change is a worldwide health threat, and patients with chronic respiratory disorders such as asthma and COPD might be more vulnerable. The reason for this includes a higher risk of symptoms and exacerbations in the future related to heatwaves, forest fires, prolonged allergen seasons and changes in vulnerability to viruses and bacteria [1]. Since climate change is a fundamental threat to all of us, finding ways to reduce carbon footprints is essential. The health sector is, unfortunately, an important contributor to global warming, accounting for between 5–7% of the total carbon footprints in countries like the UK and the Netherlands [2, 3]. Reducing carbon footprints in health is therefore important. One source of carbon footprint emissions are the propellants used in pressurised metered dose inhalers (pMDIs), HFC-134a and HFC-227ea. These two hydrofluorocarbons are powerful greenhouse gases with a potency which, depending on the gas used, is 1300 to 3000 times greater than that of CO₂ [4].

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In severe asthma, treatment with biologics resulted in only a small decrease in carbon footprint. In order to gain further environmental benefits, the carbon footprint related to inhaled therapy needs to be targeted. https://bit.ly/42CeTzk

Climate change is a worldwide health threat, and patients with chronic respiratory disorders such as asthma and COPD might be more vulnerable. The reason for this includes a higher risk of symptoms and exacerbations in the future related to heatwaves, forest fires, prolonged allergen seasons and changes in vulnerability to viruses and bacteria [1]. Since climate change is a fundamental threat to all of us, finding ways to reduce carbon footprints is essential. The health sector is, unfortunately, an important contributor to global warming, accounting for between 5–7% of the total carbon footprints in countries like the UK and the Netherlands [2, 3]. Reducing carbon footprints in health is therefore important. One source of carbon footprint emissions are the propellants used in pressurised metered dose inhalers (pMDIs), HFC-134a and HFC-227ea. These two hydrofluorocarbons are powerful greenhouse gases with a potency which, depending on the gas used, is 1300 to 3000 times greater than that of CO₂ [4].

In a paper published in this issue of the journal, Busby et al. [5] examined the carbon footprints in severe asthma and the effect of biological treatment on CO₂-equivalent (CO₂e) emissions. They found that the average carbon footprint related to asthma care was almost 0.5 tons of CO₂e. Half of this was related to short-acting beta-2-agonists (SABAs), and 31% to emergency department visits or hospitalisations. Of the 303 patients included, 70% received biological treatment. In the group given biologics, there was a reduction in exacerbations and a modest improvement in asthma control and lung function. There was also a small reduction in carbon footprints. The reduction was only 7% and was mainly related to a reduction in emergency department visits and hospitalisation. The reason that the reduction was so small was that there was no change in the use of SABAs.

The study has some limitations. The main one is that this is an observational study with no control group. Despite this, the findings are important. Like Wilkinson et al. [6], the authors showed that poor asthma control was associated with a higher carbon footprint. In both studies, the difference was largely related to the higher use of SABAs in those with uncontrolled asthma. The reason why SABAs have such a dominating role in asthma-related carbon footprints is that in most countries, SABAs are delivered by pMDIs [7]. Results from an international study showed that SABAs accounted for two-thirds of inhaler-related carbon footprints [6], and decreasing the use of SABAs is therefore important when reducing asthma carbon footprints.

There may be several explanations for why there was no reduction in the use of SABAs in the study by Busby et al. [5]. One is that the reduction in asthma control was relatively small, an average of 0.5 units. Another is that most of the patients have had asthma for many years, and frequent use of SABA in different situations might have become a habit. So, how should one proceed to decarbonise asthma care? One possibility is to use SABA delivered by dry powder inhaler (DPI) instead of pMDI. That this is possible is apparent when comparing data from different countries. In England in 2017, 96% of SABA was given by pMDI, while in Sweden, 90% was given by DPI [8]. Another option is replacing SABA with inhaled corticosteroids (ICS) in combination with formoterol. Hatter et al. [9] reported an approximately 95% reduction in the carbon footprint of asthma management and better asthma outcomes in patients treated with budesonide/formoterol DPI as a reliever compared to patients on SABA pMDI. Another advantage of replacing SABA with ICS-formoterol is that it is enough for many patients to use just one inhaler. This treatment option also makes it more likely that the patient has an optimal anti-inflammatory treatment.

Even though reliever therapy has the largest carbon footprint in asthma management, the choice of inhalers for maintenance treatment is also important. In a post hoc analysis of the Salford lung study, Woodcock et al. [10] showed that replacing pMDI with DPI-based maintenance treatment led to a more than 50% reduction in asthma treatment-related CO₂e emissions. Soft-mist inhalers are another option that is also favourable compared to pMDI from a climate perspective [11]. In a recent paper, Vartiainen et al. [12] estimated the emission from inhalers in the EU was four megatons of CO₂e. They then suggested that reducing this emission by 85% down to 0.6 megatons CO₂e was possible by a more carbon footprint-conscious choice of inhaled therapy [12]. An estimation of the carbon footprints of different treatment options for asthma patients in Global Initiative for Asthma step 2 is presented in table 1.

TABLE 1.

Estimated annual inhaler-related carbon footprints for one patient in Global Initiative for Asthma step 2 and potential reduction of CO₂ equivalent (CO₂e) emissions compared to the option with the highest CO₂e emission

	CO2e (kg)	Reduction (%)
pMDI ICS maintenance and SABA reliever	180	-
DPI ICS maintenance and pMDI SABA reliever	40	78
pMDI as needed ICS-formoterol	15	92
DPI ICS maintenance and SABA reliever	3	98
DPI as needed ICS-formoterol	0.7	99.6

Based on data from Vartiainen et al. 2024 [12]. pMDI: pressurised metered dose inhaler; ICS: inhaled corticosteroids; SABA: short acting beta-2 agonist; DPI: dry powder inhaler.

In the future, the impact of inhaled asthma therapy on the carbon footprint may be reduced if the currently used propellants HFC-134a and HFC-227ea can be exchanged for propellants that have a lower global warming potential. Two such gases are being tested: HFC-152a and HFC-1234ze(E) [13]. At present, however, the choice of inhaler is important in order to decrease the carbon footprint of asthma care. This, together with better asthma control and a reduction in emergency department visits and hospitalisation, is something the respiratory community can contribute to tackling the climate crisis.