Lawrence Berkeley National Laboratory

Current Indoor Air Quality (IAQ) regulations rely on concentration thresholds for individual pollutants, which limits their ability to capture cumulative health impacts and hinders the development of performance-based ventilation standards. Building on prior work, including Annexe D of ASHRAE 62.2, this study introduces a harm-based framework that shifts the reference from indoor concentrations to a standardised emission rate scenario. The proposed Harm Metric aggregates multiple contaminant exposures into a single health outcome expressed in DALYs·(105 pers)−1·year−1, enabling an outcome-based evaluation of ventilation performance. Applied to a representative sample of the French dwelling stock, the metric shows a median total harm of 994 DALYs·(105 pers)−1·year−1. The main contributors are particulate matter, formaldehyde, nitrogen dioxide (NO2), and radon. A ventilation sensitivity analysis demonstrates the metric’s responsiveness, with total harm decreasing to around 800 DALYs·(105 pers)−1·year−1 when airflow exceeds 350 m³·h−1 in a 100 m2 dwelling. By linking emissions, ventilation, and health outcomes, this framework supports integrating chronic exposure impacts into building standards and codes. It offers policymakers a quantitative basis for transitioning towards performance-based regulation and highlights the need for improved emission scenarios using large-scale real-world data.