Measurements of Perceived Indoor Air Quality

Chemical analysis of the composition of indoor air characterizes exposures, but sometimes this analysis may be insufficient to describe the effects of these exposures on building occupants, especially to characterize sensory effects caused by exposures to pollutants in buildings. The present chapter presents the methods used to characterize these effects. The methods using olfactometers and gas chromatography- olfactometry-mass spectroscopy (GC-O-MS) are described together with the methods using sensory panels and subjective evaluations. The latter provides direct information on how indoor air quality is perceived by building occupants, and includes assessments of acceptability of air quality and the perceived odor intensity; the assessments of acceptability can be used to determine the percentage of people dissatisfied with air quality. The limitations of methods are described together with the factors influencing the measurements using human subjects, including physical factors such as temperature and relative humidity, psychological factors such as adaptation, and procedural factors such as the number of inhalations before the assessment is completed. Possible applications of the results of measurements are shown, including characterization of emissions from building products and determination of ventilation requirements to reach a specific level of air quality characterized by the percentage of dissatisfied occupants. It is concluded that the methods presented should be considered supplementary to the chemical measurements as none of both methods can provide complete characterization of indoor air quality. When used together, they provide a more comprehensive characterization of indoor air and its quality. It is subsequently recommended that sensory evaluations of air quality and olfactometry methods (also using GC-O-MS) become part of protocols used for characterizing indoor air quality because they can capture the effects and potential consequences that other methods for measuring indoor air quality are not fully capable of measuring.