The IAIAQ project is in many ways a small scale extension and update of the EnVIE project (2003 – 2008). EnVIE developed a new robust modelling tool to evaluate the quantitative relationships between the indoor air quality (IAQ) related diseases and symptoms, indoor relevant exposure agents causing these diseases, indoor and outdoor sources of these indoor exposures and the impacts of policies to control these sources. The assessment tool is in effect a four dimensional linear matrix. The task was simplified by selecting one common metric for all four dimensions, the WHO supported ‘disability... adjusted life year’ (DALY). IAIAQ project critically assessed and in some cases omitted or amended the diseases, agents and sources of the EnVIE tool, re-evaluated the matrix coefficients, and combined the model with a new 26 (31) country European model input database, which greatly improved the comprehensibility and eased the use of the modelling tool. The EnVIE-IAIAQ modelling tool was first used to quantify the total current European IAQ related burden of disease (BoD) and to attribute it on the diseases, exposure agents and sources included in the model. (Chpt 1.2.) The given and main focus of IAIAQ was on assessing the public health impacts, i.e. achievable reductions to the above modelled IAQ BoD, of some current European IAQ policies and to predict the potential impacts of some alternative and future IAQ policy scenarios, which in a broad sense were defined in the EAHC tender. (Chpt 3.1 and 3.2.) IAIQ made also some attempts to assess the impacts of some EU funded IAQ data compiling projects on indoor air relevant EU legislation and respectively on the potential health impacts of such legislation, as well as on the impacts of some EU funded indoor air research projects (new data generating projects) on the 3 results of the EU funded data compiling projects (pre-normative projects), and further on the health impacts of the IAQ relevant EU legislation. These assessments are by necessity based on highly simplifying and thus much weaker assumptions than the policy assessments, and should, therefore, be interpreted even more critically and cautiously than the risk and policy assessments. (Chpt. 3.3.) Concerning this whole exercise, the reader should stay aware of the fact that the focus of this exercise is clearly the breadth of the assessment (to quantitatively and comparably link together a hugely complex network of health, pollution, source, building and policy issues using data of highly variable quality from 26 countries) rather than the depth of an analysis of, e.g., the emission and dispersion of and exposure to NO2 in kitchen while cooking with a gas stove. Consequently the authors readily admit that a breadth-taking amount of corners had to be and were cut to make this assessment possible within the ca. 10 month overall project execution time. We believe, however, that the results present mostly realistic levels, are properly related to each other and give correct guidance for IAQ policy development and targeting.