Agence française de sécurité sanitaire de l’environnement et du travail (Afsset) 253, avenue Général Leclerc 94700 Maisons Alfort, Union des caisses nationales de sécurité sociale, 18 avenue Léon Gaumont 75980 Paris
Between October 2003 and December 2005, the Indoor Air Quality Observatory (OQAI) conducted a survey to measure air quality in a sample of 567 French homes designed to be representative of all primary residences in continental France. Thirty physical, chemical and biological pollutants were measured. The overall aim of this work is to describe air quality in homes by simultaneously considering the entire set of pollutants measured. In this second part, we identified groups of comparable homes in terms of pollution (a homes analysis), based on Kohonen’s self-organising maps and ascending hierarchical classification methods. This analysis enabled the identification of four main types of homes polluted by volatile organic compounds (VOCs) to various degrees: The homes most polluted by several VOCs simultaneously represent 9.6% [7%; 13%] of the housing stock at a national level. This group is characterised by median concentration levels from 2 to 20 times greater than those of the complete sample for around 7 VOCs. It is divided into two subgroups, one polluted predominantly by aromatic hydrocarbons and the other by aliphatic hydrocarbons. Homes heavily polluted by one principal VOC represent 24% [20%; 28%] of the housing stock. This group is subdivided into 8 subgroups, each associated with a different VOC: 1,4-dichlorobenzene, n-undecane, 1-methoxy-2-propanol, styrene, trichloroethylene, tetrachloroethylene, 2-butoxyethanol and formaldehyde. Concentrations from 5 to 400 times greater than those of the overall sample were detected. Homes moderately polluted by several VOCs simultaneously represent 26% [23%; 31%] of the housing stock. They are characterised by median concentration twice as high as those of the complete sample for 4 to 7 VOCs. They are divided into two subgroups, one with predominantly aromatic hydrocarbons and the other with mainly aldehydes. The least polluted housing, with the lowest levels of VOCs but also of other pollutants, represents 40% [36%; 45%] of the housing stock. The other pollutants tested have very little relation to these groups.