High quality ventilation systems - a tool to reduce SBS symptoms.

The present case study refers to a larger office building in Sweden. The employees in this building, which was built in 1982, began to complain about the indoor environment around 1985-86. A preliminary examination of the building started in 1989. The preliminary investigation showed that the concrete framed floors were levelled off with self levelling compound containing casein and that there were relatively high concentrations of ammonia under the PVC-flooring. Chemical measurements showed that the total VOCconcentration in the building was relatively low but that higher concentrations could be found in certain places. Average total VOC concentration 190 pg/m³, maximum value 1230 pg/m³, minimum value 80 pg/m³. The concentration 2-ethyl- 1 -hexanol, plasticiser in PVC-flooring, was also measured. Average 2-ethyl-1 -hexan01 concentration 1 1 pg/m³, maximum value 32 pg/m³, minimum value 1 pg/m³. Moisture measurements showed that the concrete frames were dry, the relative moisture in the concrete less than 60 %. Based on these findings measures relating to the floor were considered. Next the chemical pollution in the actual ventilation system was investigated. Results showed that very high concentrations of total hydrocarbon were given off in the building at certain times and that these hydrocarbons reentered via the supply air as the ventilation system was of the recirculating type. The source of the periodically high concentrations of total hydrocarbon was a printing works located in the building. Based on these results it was decided that the device for recirculating the air in the ventilation system should be removed. The reconstruction of the ventilation system was followed up partly with technical measurements, partly with a questionnaire among the employees both before and after the reconstruction of the ventilation system. The result of the questionnaires shows that complaints about the indoor air quality decreased to a level close to a "healthy building".