Bridging the scale gap for indoor radon transport and exposure modeling: a systematic review

Indoor Radon ( 222 Rn) is a major health risk, with its accumulation in buildings influenced by energy-efficient designs and ventilation conditions. This systematic review examines indoor Rn modeling from the 1960s onward, integrating three major classes: Continuum, Data-Driven, and Mass-Balance. A unified framework at the methodological level, rather than focusing on individual tools or case-specific applications, is proposed to guide model selection and support accurate, context-specific Rn exposure assessment and mitigation strategies.