Asthma Carbon Footprint

Descriptive analysis of PBS dispensing data between 1 January 2019 and 30 November 2023, based on UK estimates of emissions per inhaler.

Findings:

• 14.4 million PBS-subsidised inhalers dispensed in 2019, increasing to 15.5 million in 2023, primarily caused by an increas in high-emission inhalers (8.2 million to 9.2 million)
• estimated emissions increased from 217 510 t to 246 934 t CO₂e
• 56.9% of dispensed inhalers were high emission in 2019 vs 59.5% in 2023
• each year, high-emission inhalers accounted for about 98% of total PBS-subsidised inhaler-related emissions
• emissions were the greatest for SABA inhalers (98% in high emissions inhalers, 57% of all inhaler-related emissions) and combined ICS/LABA (49% in high-emission inhalers, 34% of all inhaler-related emissions)

PBS-subsidised inhaler dispensing rates were:

• higher in non-metropolitan than metropolitan areas(but emissions were higher in metropolitan areas due to a larger number of inhalers dispensed).
• higest in Tasmania (693 per 1000 population in 2023) then South Australia (632 per 1000) and lowest in the Northern Territory (355 per 1000 population) and Western Australia (383 per 1000 population)
• higher for females than males (proportion of high emission inhalers also higher for females)

The proportions of high emissions inhalers dispensed were largest in South Australia (63–65%) and the Northern Territory (59–64%) and smallest in the Australian Capital Territory (53–57%) and Western Australia (52–56%).

The age group dispensed the largest proportion of PBS‐subsidised inhalers were people aged 60–79 years (43–45% of all PBS‐subsidised inhalers dispensed; high emissions inhalers, 50–54%).

Note: study was limited by the omission of over the counter sales (for SABA) and some missing data.

TSANZ has published a position statement advocating for the use of DPI or soft-mist inhalers, as ‘green inhalers’. It is a good resource for deep understanding of the carbon footprint of inhalers, current practices/context and their impact. Some facts include:
– Over 8 millions of pMDIs were dispensed in Australia in 2022
– Percentage of inhaler doses delivered by pMDI exceeds 80% in Australia, United States and United Kingdom
– One person changing from MDI to DPI preventer is similar to changing from a petrol to a hybrid car, or going from meat-eater to vegetarian, over a full year.
– Research and development is also underway to commercialise MDIs with low-emission propellants, with carbon footprint almost 10 times smaller
– Two thirds of inhaler related greenhouse gas emissions are related to high reliever use, which could be decreased by better preventer adherence and asthma control.

The statement includes strategies to mitigate the impact, including Prescribing strategies (including the use of AIR therapy) and Recycling and reuse.

A Victorian retrospective pharmacy-based database search of all inpatient inhaler dispensing from 1 July 2022 to 30 June 2023 at The Royal Melbourne Hospital.
Findings:
– 9,246 inhalers were dispensed in a year, of which 79% were MDIs and accounted for 99% of the total inhaler carbon footprint
– Salbutamol MDI (51%), ipratropium MDI (12.5%) and budesonide/formoterol MDIs (8%) were the most frequently dispensed inhalers, accounting for 71.5% of total inhalers dispensed
– Tiotropium respimat (406 inhalers) and budesonide-formoterol DPI (379 inhalers) were the most frequently dispensed SMI/DPIs but accounted for only 4.39% and 4.01% of dispensed inhalers respectively
– the Carbon footprint of MDIs used for asthma and COPD at the hospital was equivalent to providing electricity to 50 homes for a year.
Conclusion: the environmental impact of inhaler choice should be considered in decision-making around prescribing

A study in 668 adults asthma patients looked at the carbon footprint of inhalers and found that as needed budesonide-formoterol DPI (e.g. Symbicort) resulted in:
– 95.8% less carbon emission than as-needed salbutamol pMDI (e.g. Ventolin)
– 93.6% less carbon emission than maintenance budesonide DPI + as-needed salbutamol pMDI

Note: this is a rather small study.

A study including 236K participants with poorly controlled asthma in the UK reported that poorly controlled asthma results in:
– 3 times the carbon emissions of well-controlled asthma (on average)
– Excess was largely driven (90%) by inappropriate use of SABA.

Researchers analysed the carbon footprint of inhaled medications in Europe using 2020 European sales data, and estimated the emissions of different treatment regimens on Global Initiative for Asthma (GINA) step 2.
Findings:
– There is potential to reduce the carbon footprint of inhaled medications by 85% if DPIs are preferred over pMDIs.
– For moderate asthma, as-needed ICS/LABA had a substantially lower annual carbon footprint (0.8 kg CO2e) than the more traditional maintenance ICS + as-needed SABA (2.9 kg CO2e)
– Emissions from pMDIs in the EU were estimated to be 4.0 megatons of carbon dioxide equivalent (MT CO2e) which could be reduced to 0.6 MT CO2e if DPIs were used instead