In an occupational hygiene study of 25 workplaces with exposure to PAHs, 219 personal airborne samples were collected and showed the levels of nine carcinogenic PAHs ranged from 0.01 to 35.93 μg m−3 8 h TWA with a median of 0.12 μg m−3 8 h TWA. Levels of total PAH (the sum of 17 compounds) were found to be dominated by naphthalene and were insensitive to changing levels of nine carcinogenic PAHs. Measurement of BaP, a single PAH, was well correlated to levels of the nine carcinogenic PAHs and is a marker of exposure and risk. In this study the levels of BaP ranged from