Sampling and Analysis Artifacts Caused by Elevated Indoor Air Polychlorinated Biphenyl Concentrations

Polychlorinated biphenyl (PCB) concentrations were measured in the indoor air of several public buildings in Bloomington, IN. The concentrations ranged from 5 to 300 times higher than outdoor concentrations, and the indoor air PCB levels were highest in buildings with the earliest construction dates; see Figure 2. These elevated indoor air PCB levels have caused contamination in sample preparation as well as artifacts in sample collection. PCBs in procedural blanks in a laboratory with an indoor air PCB concentration of 6 ng/m3 averaged 1 order of magnitude lower than those measured in a laboratory with an indoor air PCB concentration of 300 ng/m3. Air sampling conducted on the roof of a building with high indoor air PCB concentrations and roof-top ventilation gave PCB concentrations that were approximately five times above ambient levels. However, sampling on the roof of another building without roof-top ventilation gave PCB concentrations that were not artificially elevated. We recommend measuring the i...