An experimental simulation of an early rock wool/slag wool production process

This paper presents the results from an experimental simulation of a rock wool production process with conditions similar to those operating in the 1940s. Data are presented to illustrate the reduction in airborne fibre levels when oil was added to the product and the effect of workers handling batches of insulation material. Addition of oil to the product resulted in a reduction in the airborne fibre levels from 3 to 9 times in different situations. The time-weighted average concentration during the period of the experimental production work was approximately 1.5 F_r ml^-1 with oil added and approximately 5 F_r ml^-1 without oil. The handling of MMMF in a small enclosed cabin gave rather higher levels, approximately twice those measured in the production experiment. The exposures while handling blocks of insulation (intended to simulate discontinuously produced material) compared with continuously produced material were not substantially different. External factors which could influence the fibre levels were monitored. These data are discussed in relation to a mathematical model of past exposure presented by Dodgson et al. [Ann. occup. Hyg. 31, 567-582 (1987)] at this symposium.