CRITICAL ASPECTS ON THE SIGNIFICANCE OF MICROBIAL VOLATILE METABOLITES AS INDOOR AIR-POLLUTANTS

The effect of microbial growth in building materials on airborne level s of volatile organic compounds (VOCs) was demonstrated by theoretical ly calculating indoor air concentrations of selected VOCs for rooms wi th and without microbial contamination. The recommended indoor air lev el for individual VOCs was also estimated on the basis of their sensor y irritation potency. Furthermore, the irritation potency for the mixt ures of certain compounds (microbial volatile metabolites, MVOCs) at a irborne concentrations measured in problem buildings was evaluated. Th e theoretical airborne concentrations of certain compounds, which are generally regarded as MVOCs, were estimated to be only about 1% higher in the biocontaminated rooms than in those with moist sterile materia ls. In fact, no individual VOCs indicated exclusively microbial contam ination, but they could also be emitted even from sterile, moist const ructions. Exposure to mixtures of the selected non-reactive VOCs at th e theoretical airborne concentrations would not result in sensory irri tation in humans, and, thus, microbial growth in constructions should not increase the probability of irritating symptoms considerably. The data on MVOC concentrations measured in some problem buildings also su pported this idea. Irritation would be expected when the airborne conc entrations of single non-reactive compounds approach a level of hundre ds of mu g/m(3) or mg/m3. (C) 1998 Elsevier Science Ltd.