Benzalkonium chloride (BKC) and copper are the main components used in a preservative treatment of wood by pressure process. We examined the simultaneous extraction of both materials and the methods of analysis. Air was passed through an impinger using purified water as an absorber. Levels of BKC were analyzed using high performance liquid chromatography, and levels of copper were measured using ICP optical analysis. Surveys were conducted on four houses built using lumbers treated with the

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... ervative. This measurement method was found to have considerable validity. Concentrations of the relevant compounds were found to be very low; it seems reasonable to conclude that the possibility of air contamination due to the presence of compounds volatilized from the lumber is small. It is necessary to cool the impinger when it is estimated that the absorber has evaporated.