Often, a first step for health systems in their journey to decarbonization is to identify their main emissions sources to prioritize interventions to reduce them. At a country level, the driving approach to a first-time emissions baselining should use national-level data, with facility-level data complementing this approach when available. At the facility level, building this capacity is key and should be pursued at a feasible pace. Baselines at both levels (national and facility-based) will likely have data limitations at the beginning - but the process, data collection tools, and analysis can and should be improved over time. Ultimately, the approach to be used will largely depend on a country’s objectives, data availability and access, and their internal capacity.