INTRODUCTION: Faced with the challenges of climate change, countries are seeking to decarbonise their economies. A greater understanding of what comprises the carbon footprint of care in healthcare systems will identify potential strategies for reduction of greenhouse gas (GHG) emissions. In respiratory care, the focus has been on preventer inhalers, thereby omitting contributions from other aspects such as healthcare resource utilisation (HCRU) and reliever inhaler use. The healthCARe-Based envirONmental cost of treatment (CARBON) programme aims to provide a broader understanding of the carbon footprint associated with respiratory care. METHODS: CARBON will quantify the carbon footprint of medications and HCRU among approximately 2.5 million patients with respiratory diseases from seven ongoing studies spanning more than 40 countries. Across studies, to obtain the carbon footprint of all inhaled, oral, and injectable medications, SimaPro life cycle assessment software modelling resource and energy consumption data, in addition to Ecoinvent(®) data sets and certified published studies, will be used. The carbon footprint of HCRU in the United Kingdom will be estimated by applying the methodology and data obtained from the Sustainable Healthcare Coalition Care Pathway Guidance. PLANNED OUTCOMES: In asthma, CARBON studies will quantify GHG emissions associated with well-controlled versus not well-controlled asthma, the contribution of short-acting β(2)-agonist (SABA) reliever inhalers (and their potential overuse) to the carbon footprint of care, and how implementation of treatment guidelines can drive improved outcomes and footprint reduction. In chronic obstructive pulmonary disease (COPD), CARBON studies will assess the impact of exacerbation history on GHG emissions associated with HCRU and SABA use in subsequent years and estimate the carbon footprint associated with all aspects of COPD care. CONCLUSION: CARBON aims to show that the principle of evidence-led care focused on improvement of clinical outcomes has the potential to benefit patients and the environment.