ORM (OPTIMAL REMOVING OF MOISTURE FROM WATER DAMAGED BUILDING CONSTRUCTIONS) - MVOCS

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1 ORM (OPTIMAL REMOVING OF MOISTURE FROM WATER DAMAGED BUILDING CONSTRUCTIONS) - MVOCS O-A Braathen 1*, N Schmidbauer 1, C Lunder 1, P Blom 2, J Mattsson 3 1 Norwegian Institute for Air Research, Kjeller, Norway 2 Norwegian Building Research Institute, Oslo, Norway 3 Mycoteam as, Oslo, Norway ABSTRACT The Norwegian ORM project was focussed on establishing optimal procedures for removing moisture from damaged constructions with as low possibility for microbiological activity as possible. Different floor coverings were water damaged and contaminated with a mixture of spores and then dried in different ways. During the drying process, the emissions of MVOCs were measured and the moulds were studied. In this paper, results of the measurements of MVOC-emissions from a parquet sample dried in a natural way, are presented. The measurements showed different emission profiles during the 85 days drying process for volatile and semi-volatile MVOC-compounds. The emission of semi-volatile MVOCs was detectable for much longer periods than the emission of volatile compounds. The results of the study show that MVOC-investigations can be used as a non-destructive way to indicate the presence of active moulds inside building constructions and thus help the practitioners to choose the best remediation strategy. INDEX TERMS MVOCs, Emissions, Water damage, Removal of moisture INTRODUCTION In order to enable practitioners to remediate water damages in buildings correctly during the crucial first phase, the project ORM was carried out in Norway. The work was focussed on establishing optimal procedures for removing moisture from damaged constructions with as low possibility for microbiological activity as possible. This was done both by carefully designed laboratory experiments and by studying the remediation of actual water damages in buildings. The present paper describes the controlled measurements of emissions of MVOCs (Microbial Volatile Organic Compounds) during the drying of the water-damaged materials. METHODS In the laboratory, pieces of floor constructions, consisting of different floor coverings mounted on various materials, were exposed to simulated water damage, either by total immersion in a container filled with tap water or directly by running tap water. The materials were exposed to water for about 68 hours, corresponding to a weekend from Friday afternoon to Monday morning. The samples of floor construction were exposed to a mixture of spores of various moulds in water ( spores pr. ml). The moulds included in the mixture were: Aspergillus versicolor, Chaetomium indicum, Cladosporium cladospoides, Paecilomyces variotti, Penicillium chrysogenum, Stachybotrys chartarum and Trichoderma viride. These * Contact author [email protected] 408

2 moulds were selected because they often occur in connection with water damages of building materials. After being water damaged and contaminated, the pieces were dried in different ways (both natural drying and mechanical drying) for 85 days. During this period the moisture content was measured and moulds were studied. Emissions of MVOCs (microbiological volatile organic compounds) were sampled on adsorption tubes (Tenax TA). Measurements were done by thermal desorption using an ATD400 from Perkin Elmer, followed by combined gas chromatography/mass spectrometry (GC/MS) using a HP GCD instrument. Quantification was based on an external toluene standard. About 44 different possible MVOCs were included in this study. A total of six series of tests of floor construction samples were carried out during the ORM study. The samples tested represented different types of floor constructions with various floor coverings mounted on various materials. In this paper, only the results for natural drying of a sample of parquet will be presented. RESULTS Through the life cycle, moulds will continuously emit volatile organic compounds (MVOC) to the air. There are, however, large variations in the composition and strength of this emission. One example is the variation through the various life stages of a colony (initial growth phase, established colony, drying of the colony). The consequence of this is that the term "MVOC" includes a large number of compounds. Some of these compounds are rather specific for moulds, while other MVOC-components may also have emissions sources such as building materials or furniture. However, identification of a sufficiently large number of the possible MVOCs in an indoor air sample, constitutes a very strong indication of microbial activity. The selected possible MVOCs are shown in Table 1. The 44 compounds listed cover a broad range of physical and chemical properties. 409

3 Table 1. Volatile organic compounds that may have moulds as emission sources (MVOC). Compound Furan Camphene 2-Methylfuran 2-Heptanone 3-Methylfuran 2-Pentylfurane 3-Buten-2-one α-terpinene 2-Butanone 2-Octanone 2-Methyl-3-buten-2-ol α-terpinolen Tetrahydro-2-methylfuran 2-Methyl-3-octanone 2-Ethylfuran Hexylfuran 2,5-Dimethylfuran Fenchone 3-Methyl-2-butanone 2-Nonanone 2-Pentanone D-Fenchyl alcohol 3-Pentanone Camphor 2-Pentanol 2,6,6-Trimethylbicyclo(3.1.1)heptan- 3-one Pyrazine 4-Terpineol 4-Methyl-2-pentanone Estragole 2-Methyl-3-pentanone 1-Borneol 3-Methyl-2-pentanone α-terpineol 2-Hexanone 6,6-Dimethyl-bicyklo[3.1.1]hept-2- en-2-carboxyaldehyde Methylpyrazine α-α-4-trimethylbenzenemethanol Tetrahydro-2-furanmethanol 2-Pentanoylfuran 2-Butylfuran 6-Undecanone α-fenchene Verbenone In the present paper, the emission of MVOCs from a sample of parquet were studied for 85 days after the sample was water damaged and sprayed with the mixture of spores of various moulds in water. During this 85 days period, the sample was dried by in a "natural way", without any forced drying or elevation of the temperature. The flooring material studied was mounted on a frame, which as far as possible, resembled a normal floor construction, including materials. The mixture of spores was added inside the frame (beneath the floor covering). The emission of MVOCs was studied by measuring the equilibrium concentrations inside the frame after 2, 4, 7, 9, 11, 16, 23, 52, and 85 days. Between measurements, the constructions were dried under controlled indoor conditions. During the measurements, the constructions were placed in small emission chambers with controlled purified airflow. In Figure 1 and 2, the results for 2-pentanone and camphene are shown. In the figures, the actual measurement results are marked and the lines between the measured results are interpolated. 410

4 2-Pentanone µg/m Day Figure 1. The measured concentrations of 2-pentanone during the 85 days of natural drying of the parquet sample (the results are marked and the lines represent interpolation between results.) 2-Pentanone is a rather volatile MVOC component. Figure 1 shows maximum emission of 2-pentanone after about 7 days. After the maximum, the emission decreases and after about 23 days the emission is negligible. The emission profile shown in Figure 1 is rather simple with one definite maximum and a simple curve shape. 250 Camphene 200 µg/m Day Figure 2. The measured concentrations of camphene during the 85 days of natural drying of the parquet sample (the results are marked and the lines represent interpolation between results.) Camphene is significantly less volatile than 2-pentanone. In Figure 2, the emission profile for camphene is shown. It can be seen that the emission is significantly reduced during the first 411

5 23 days, but it is not negligible before after about 50 days. Possible explanations for the much longer emission time for camphene compared to 2-pentanone, may be the difference in volatility or variations in the composition of the emissions from the moulds. The profile for camphene does not show a clearly defined maximum, but a rather complicated structure. The same effect was seen for other semi-volatile MVOCs and there may be several reasons for this. It may be due to the sampling, since there were differences in the conditions during the equilibration period before sampling (the period where the constructions were placed inside the small emission chambers) or it could be caused by direct variations in the emissions. However, the emission of the semi-volatile MVOCs is easily detectable during this phase. Measurements of α-pinene, which is not considered a possible MVOC, show an emission profile that resembles the profile for camphene, including the complicated structure around the maximum. It is therefore reasonable to presume that this complicated structure is due to the sampling design rather than actual fluctuations in the composition of the emission. DISCUSSION In order to assess the usefulness of measurements of emissions of MVOCs as a nondestructive tool to study hidden microbiological activity inside constructions, emissions of 44 possible MVOCs were studied The results of the total ORM study showed that microbiological activity, and therefore also the emissions of MVOCs, varied considerably between different samples and were very dependent on how the drying of the water damaged material was carried out. In this paper, only the results for a parquet sample dried in a natural way are presented. The studied MVOCs, which ranged from very volatile compounds to semi-volatile compounds, showed different emission profiles during the 85 days drying process. For semivolatile compounds, the emissions were detectable 50 days after the water damage. In real life situations, the emission could last much longer since new additions of water will often occur and the drying process will in many cases, be much longer than in the laboratory. In cases were water damage and corresponding mould growth inside building constructions, are suspected, but not visually detectable, detection of MVOCs in indoor air can be used to indicate the need for further actions, such as opening of building constructions or removal of water damaged materials. This study underlines the importance of including a large number of MVOCs, covering the whole range of physical and chemical properties, in such investigations. In this way, MVOCs may give indication of mould growth for a long period of time after the water damage occurred. Studies of MVOCs in air are non-destructive and thus often a comparatively cheap way to acquire the information necessary for choosing the best remediation strategy. CONCLUSIONS AND IMPLICATIONS In conclusion, the results of the ORM project show that active mould colonies in closed spaces in building constructions will emit MVOCs. MVOC-studies can therefore be used as a non-destructive way to indicate the presence of active moulds and thus help the practitioners to choose the best remediation strategy. It is, however, necessary to include a large number of MVOCs, covering the whole range of physical and chemical properties, in such investigations. 412

6 ACKNOWLEDGEMENTS The ORM project is sponsored by the Norwegian State Housing Bank, the insurance companies If, Gjensidige Nor, Vesta and Sparebanken1 Forsikring and the restoration contractors Polygon and Munthers AB. 413