Pentachlorophenol in indoor environments. Does a single measurement of airand dust concentrations represent the contamination?

In order to be able to make a decision, as to whether a room or building ha s a health-endangering pentachlorophenol (PCP) concentration, usually the P CP concentrations in air and settled dust are measured. The variability of the PCP concentration in indoor air and dust was studied. Air and dust samp les were taken from 75 rooms in 30 buildings with suspicion of application of PCP-containing wood preservatives. Sampling was repeated four times with in 18 months. Thirty-six rooms were reconstructed within the study; 39 room s had unchanged contamination status during the study. The four times repea ted measurements of PCP concentrations in air and dust in these rooms showe d large variations of the measured values. The variability of the results i s to a large extent in the same range as the measured values. The observed relative standard deviation of the PCP concentrations in air and dust does not depend on the average PCP concentration detected in the individual room s.