Sensory and chemical characterization of VOC emissions from building products: impact of concentration and air velocity

The emissions from five commonly used building products were studied in sma ll-scale test chambers over a period of 50 days. The odor intensity was ass essed by a sensory panel and the concentrations of selected volatile organi c compounds (VOCs) of concern for the indoor air quality were measured. The building products were three floor coverings: PVC, floor varnish on beechw ood parquet and nylon carpet on a latex foam backing; an acrylic sealant, a nd a waterborne wall paint on gypsum board. The impacts of the VOC concentr ation in the air and the air velocity over the building products on the odo r intensity and on the emission rate of VOCs were studied. The emission fro m each building product was studied under two or three different area-speci fic ventilation rates, i.e. different ratios of ventilation rate of the tes t chamber and building product area in the test chamber. The air velocity o ver the building product samples was adjusted to different levels between 0 .1 and 0.3 m s(-1). The origin of the emitted VOCs was assessed in order to distinguish between primary and secondary emissions. The results show that it is reasonable after an initial period of up to 14 days to consider the emission rate of VOCs of primary origin from most building products as bein g independent of the concentration and of the air velocity. However, if the building product surface is sensitive to oxidative degradation, increased air velocity may result in increased secondary emissions. The odor intensit y of the emissions from the building products only decayed modestly over ti me. Consequently, it is recommended to use building products which have a l ow impact on the perceived air quality from the moment they are applied. Th e odor indices (i.e. concentration divided by odor threshold) of primary VO Cs decayed markedly faster than the corresponding odor intensities. This in dicates that the secondary emissions rather than the primary emissions, are likely to affect the perceived air quality in the long run. Some of the bu ilding products continued to affect the perceived air quality despite the c oncentrations of the selected VOCs resulted in odor indices less than 0.1. Therefore, odor indices less than 0.1 as an accept criterion cannot guarant ee that a building product has no impact on the perceived air quality. (C) 1999 Elsevier Science Ltd. All rights reserved.