Everyone has a right to safe living environment, including indoor air quality (IAQ) that does not endanger the health. Nevertheless the recent European EnVie project estimated that the annual burden of disease (BoD) related to inadequate IAQ is 2 million disability adjusted life years (DALY) in EU27 in 2008. Reducing this BoD is a high priority in the European health policies. Ventilation is the key technology to control IAQ including thermal conditions and humidity, structural moisture and mould growth, extraction and dilution of emissions from indoor sources and infiltration of ambient air pollution indoors. HEALTHVENT project is developing European ventilation guidelines to protect health. The current paper presents the modelling approaches developed as part of the project to estimate the impact of the proposed guidelines on the burden of disease. The results highlight the dual role of ventilation in diluting indoor generated pollutants while at same time introducing outdoor air pollution indoors. ; JRC.I.1-Chemical Assessment and Testing