Towards a harmonized database of indoor air contaminant concentrations: Methods and application to CO2 - Gabriel Rojas; Reto Stauffer; Núria Casquero-Modrego; Marcel Loomans; Marc Abadie; Ibrahim Alhindawi; Francesco Babich; Gabriel Bekö; Marie Coggins; Bart Cremers; Bernhard Damberger; Timm Freundorfer; et al. (Building and Environment, 2026)