Occupational exposure to carbon black: a particulate sampling study

In order to determine the particulate exposure levels within carbon black production plants, a sampling survey involving workers from seven carbon black producers was initiated in late 1979. A total of 1,951 acceptable samples (1,564 total dust and 387 respirable dust) were collected from closed-face filter cassettes worn by carbon black workers performing normal work operations. A one-centimeter cyclone separator was employed for respirable dust sampling. Overall sampling distributions of the time-weighted average values generated from the survey were best described by the log-normal distribution. Characterization of the particulate exposures to workers is provided for the various areas of employment and specific jobs within these areas. Summary geometric mean time-weighted average values by area of employment and by job category are well within the carbon black permissible exposure limit (PEL) of 3.5 mg/m3. Identification of those job categories subject to relatively higher particulate exposures, and quantification of these exposures, is essential to the effective industrial hygiene monitoring and control of worker exposures.