Sensory evaluation in test chambers: Influences of direct and indirect assessment

Abstract

The release of volatile organic compounds from building products may influence the perceived air quality in the indoor environment. Consequently, building products need to be assessed for the acceptability of emitted odors. The standard ISO 16000-28 describes the evaluation of perceived odor in test chambers with trained panelists, being calibrated with diluted acetone. For the direct odor assessment, ISO 16000-28 requires an air flow of 0.6–1.0 l/s at the chamber outlet. To meet these conditions under normal air exchange rates, the minimum chamber volume is about 3 m³. If smaller chambers are used, air must be collected into containers for an indirect assessment. Procedures for the handling of the containers are provided in the ISO standard. Nevertheless, the indirect assessment method has a number of pitfalls and drawbacks. Experiments with sampling-container materials such as Nalophan™ and Tedlar® and different sampling techniques (continuous vs. discontinuous) have shown that the composition of sampled air might be influenced by the container material due to sink effects and leakage. The recoveries of the target VOCs in the sampling container decreased in dependence of decreasing vapor pressure and increasing octanol/air distribution coefficient.1-butanol and 1-hexanol have high recovery rates in Nalophan™ containers. These substances therefore appeared to be suitable for investigations into the synergistic odor effect. It could be shown that mixtures of 1-butanol and 1-hexanol have no clear additive effect in the sensory evaluation. This calls into question the practical relevance of an odor guide-value concept based on individual substance evaluations.