The French indoor air quality observatory (OQAI) was set up by the French authorities in 2001 with the objective to collect data on indoor pollutants in various indoor environments to be used for public policies. Funded exclusively by public funding, the OQAI is coordinated by the scientific and technical center for building (CSTB) and involved an extensive network of partners across France in charge of the field campaigns and the laboratory analyses. To date, nationwide surveys were carried out in dwellings (2003-2005), schools (2013-2017), and office buildings (2013-2017). The next survey to be started early 2019 will focus on age care facilities. Moreover, the OQAI has been coordinating since 2012 a permanent data collection on indoor air quality and ventilation in energy-efficient buildings. This topical session summarizes the last OQAI results, with a dedicated focus on ventilation.