Trends in levels of inhalable dust exposure, exceedance and overexposure in the European carbon black manufacturing industry

In an attempt to investigate the relationship between exposure to carbon bl ack and respiratory morbidity, a study of the complete carbon black manufac turing industry in Western Europe was commissioned. As part of this study, a large number of personal inhalable (n = 8015) dust exposure measurements was taken during three phases of data collection between 1987 and 1995, Rep eated measurements on the same worker were taken in the last two phases, wh ich enabled the estimation of the within- and between-worker components of variance. Simultaneously, the fixed effects of phase and factory were estim ated using mixed-effects analysis of variance. The results show that the personal inhalable dust exposure has reduced sign ificantly since the first phase of the study. In addition, the interaction term between phase and factory was significant in most job categories, conf irming that the reduction of exposure was not equal across all factories. When all factories were considered together, the probability that the mean exposure of a randomly selected worker (overexposure) or the probability th at the exposure on a randomly selected day for a randomly selected worker ( exceedance) was higher than 3.5 mg m(-3), was 10% or less for all job categ ories in the last phase. However, when the factories were considered separa tely, it appeared that the probability of overexposure or exceedance was in excess of 10% for the job categories 'Fitter/Welder', 'Warehouseman' and ' Site crew' for a number of factories. Therefore, even though exposure level s of inhalable dust have dropped considerably across the whole carbon black manufacturing industry in Western Europe, further reductions in exposure l evels are required in these areas to make sure that the probability of over exposure and exceedance falls below a level of 10%, (C) 2000 British Occupa tional Hygiene Society. Published by Elsevier Science Ltd. All rights reser ved.