Since September 2000 and on medical request, the Regional Unit for Indoor Pollution Intervention (French acronym: CRIPI) conducts indoor pollution analyses in Brussels dwellings. Currently, more than 2200 interventions were performed. These interventions are based on a multifactorial approach including amongst others a questionnaire on Health and Environment to be completed by the patient, chemical and microbiological analyses. In order to facilitate result interpretation, CRIPI developed and uses several indices. Concerning the chemical pollutants, a global index based on six categories of Volatile Organic Compounds (COVs) is applied. Concerning the microbial pollutants, several indices are also available: 1) fungal spores in air, 2) settled dust on furniture, 3) dust present in/on mattress, carpets or armchairs. Both chemical and microbiological indices allow to identify anomalies in the patients environment, which can help in the communication of effective sanitation procedures to the patient. Concerning the physician, this environmental assessment can also help to refine his diagnosis.