The objective of this study was to test a new office space where the environmental conditions could be well controlled- a "field laboratory", located at Mid Sweden University in 6stersund. To test the laboratory, the same experiment that had been carried out earlier at the Technical University of Denmark (DTU) was repeated. A further objective was to test whether the earlier results from DTU showing a negative impact of increased indoor air pollution on perceived air quality, Sick Building Syndrome (SBS) symptoms and performance could be repeated. In the experiment, the air pollution was altered in the office by introducing or removing a pollution source, a 20-year-old used carpet, used earlier in DTU's study. All other environmental parameters were kept unchanged. Thirty female subjects performed simulated office work in the office under two exposure conditions. They also assessed perceived air quality and intensity of SBS symptoms several times during exposure. The exposure lasted 4.6 h in the afternoon. The subjects could not see whether the source was present or not and remained thermally neutral by adjusting their clothing. When the pollution source was absent, there was a lower percentage dissatisfied with the air quality (P<0.02). Increased intensity of "dizziness" (P<0.03) and "difficulty in thinking clearly" (P<0.04) were significantly associated with the exposure during which the pollution source was present in the office. Also at this exposure subjects typed less (P<0.02) and made more errors when adding numbers (P<0.02). In conclusion, the office serving as a field laboratory operates reliably and the results obtained in the present study support the earlier findings of DTU.