Peoples' perceptions of indoor air quality, as reported on questionnaires, have often been used as subjective indicators of the quality of indoor air. The questionnaires normally ask subjects to rate air quality on a scale ranging from clearly acceptable to clearly unacceptable. Acceptability of indoor air is affected by various factors including ventilation rate, the emission rates of indoor pollutants, and air temperature and humidity. Research, performed primarily in the laboratory [18, 19, 32, 33, 35, 36], has found that improved perceptions of, or satisfaction with, indoor air quality are associated with improvements in some aspects in work performance. In this research, performance of some tasks increased by approximately 1% for each 10% reduction in the percentage of the occupants dissatisfied with indoor air quality. However, it is not known whether an increased satisfaction with indoor air actually causes people to work better. It could be that the indoor environmental exposures, e.g., pollutants, directly cause both poorer work performance and dissatisfaction with indoor air, leading to a correlation of performance with perceived air quality.