City dwellers spend most of their time inside buildings or other enclosed spaces, where various types of pollution are believed to be responsible for numerous health effects. The Indoor Air Quality Observatory (OQAI) was established to contribute to improving knowledge about population exposure and identifying the environmental and behavioral determinants of this exposure, with the aim of assessing and managing health risks. The main objective of this study is to analyze the influence of the space-time budget (STB) and methods for assessing indoor air pollutant concentrations on the estimation of people’s exposure during the time they spend in their homes. The proposed solutions may vary depending on the objectives of the public health studies that use them.