After moving into a new office building, employees complained about eye irritations, sore throats and unspecific symptoms. They were concerned about visible dust as a potential cause of adverse health effects. An external working group was appointed to investigate indoor air pollution and health complaints and to suggest measures to improve the situation. Air samples and floor dust samples for analysis of organic compounds were collected in three offices. Bimonthly during 8 months, measurement campaigns were conducted to assess the trend of air pollutants. A questionnaire was administered concerning environmental conditions at the work place and complaints before and after moving into the new office building. Overall the concentrations of volatile organic compounds (VOC) and formaldehyde were fairly low. However, initially high concentrations (4300-7800 mg/kg) of tris-(2-butoxyethyl)-phosphate (TBEP) and diethylhexylphthalate (DEHP: 980-3000 mg/kg) were found in dust samples. The coating of the rubber floor was identified as the source of TBEP, while no single predominant source of DEHP was found. Results of the questionnaire demonstrated an increased irritation of the mucous membranes and a reduction of well-being after the employees had moved into the new building. Perception of low relative humidity and high temperature as well as unpleasant odors were associated with respiratory complaints. After removal of the coating of the rubber floor throughout the whole building, a reduction up to 90% of TBEP in the dust samples was found. In spite of several attempts, no such marked reduction was achieved with the concentration of phthalates. Although there was no significant association between visible dust exposure and increase of complaints after moving in, room climate conditions that could increase the deposition of dust in the airways were associated with the complaints. Hence it cannot be ruled out that fine dust containing TBEP together with unfavorable indoor factors were responsible for the development of the complaints.