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and Biocides in Indoor Air – Analysis and Verification. Bengt Wessén Joakim Honkanen Maria Nilsson Åsa Sisell PEGASUS LAB AB, P.O.Box 97, 751 03 Uppsala, Sweden INTRODUCTION. In problem buildings the quality of indoor air is usually low. In Scandinavian buildings a large proportion of these problems are caused by damp conditions followed by microbial growth. The microbial emissions are commonly perceived as moldy odor. Sometimes however the building constructor have used toxic preservatives in the building material in order to avoid microbial growth. Many of these preservatives are toxic to humans and also emit volatile chemicals. Many of these chemicals may be perceived as moldy odors. This paper describes a method to identify and verify the cause of perceived moldy odor in indoor air. 
VOC-emission from floor construction. METHODS Sampling of VOC-profile. Samples were collected with portable constant flow pump. Air samples are collected by sucking air through parallel fitted adsorbent tubes containing Anasorb 747 (beaded carbon) and/or XAD-2. In non-industrial environments the sampling air volumes are >100 liters with airflow of 500 ml/min. The sampling of trapped construction air was made by collecting the air below a desiccator cover or by drilling a small hole (Æ 6 mm) into the construction and place the adsorption tube into the hole. 
VOC-sampling from room air and floor construction. The Anasorb 747 tubes are analyzed qualitatively and quantitatively concerning MVOC (microbial produced volatile organic compounds). The adsorbent is extracted with methylenechloride. The extract is separated with gas chromatography (GC) and detected with mass selective detector (MS) in selected ion monitoring (SIM) mode (1). The XAD-2 tubes are analyzed qualitatively concerning PAH, chlorophenols and chloroanisols with a method similar to the MVOC method. The analytical results of these air samples are later verified through analysis of the building material. 
Sampling of building material Analysis of microbial biomass. The MVOC compounds are verified through microbial biomass measurements. The building material is characterized for odor. A randomly chosen representative area of the building material is extracted with a sterile particle free water solution containing 0.05% (w/w) Tween 80 in an ultrasonic bath for three minutes. Total microbial biomass is analyzed by staining the sample with acridine orange. The viable fraction is analyzed as C.F.U. (2) 
Microbial biomass Analysis of wood preservatives. The wood preservatives like PAH, chlorophenols and chloroanisols are verified at the laboratory through Solid Phase Microextraction (SPME) or extraction of the material followed by GC-MS in SCAN mode. 
SPME-sampling of building material RESULTS The VOC-profile of eight problem buildings was analyzed both for the indoor air and trapped construction air. Six of these buildings showed impact of microorganisms. The acridine-orange method could verify the microbial growth in those buildings while the C.F.U. only verified the source in three of these buildings. Two of the eight buildings showed a VOC-profile including wood preservatives. This was verified by analyzing the emission from different building material. SUMMARY This approach to causal relationships of indoor odor problems presents a method where the air is sampled on the same device and later analyzed in the laboratory. The combination of parallel sampling of indoor air on Anasorb 747 and XAD-2 allows for analyzing and screening the indoor air for microbial volatile organic compounds (MVOC), polyaromatic hydrocarbons (PAH), chlorophenols and chloroanisols. The follow up on the laboratory results involves material sampling and verification. It is very important in microbial analysis to include a method for total biomass as the C.F.U. method seriously underestimates the true amount of microbial biomass. REFERENCES 1. Wessén, B, Ström, G. and Schoeps, K-O. 1995. MVOC - Profiles - A Tool for Indoor-Air Quality Assessment. In: Indoor Air an Integrated Approach edited by Morawska, L. and Bofinger, N.D. and Maroni, M., pp 67-70. 2. Ström,G, Palmgren, U, Wessén, B, et al. (1990).The sick building syndrome-An effect of microbial growth in building constructions? In Indoor-air 90, D.S.Walkingshaw ed. Vol 1, pp 173-78. TILLBAKA |