[Occupational exposure to asbestos-containing dust at the plants manufacturing and using asbestos products during the years 1986-1989].

During 1986-1989, dust levels at workplaces in 19 plants manufacturing or using asbestos products in Poland were measured. Total dust concentrations were determined by the gravimetric method and respirable asbestos fibre concentrations were determined by the phase contrast optical microscope method (PCOM). Air was sampled at the breathing zones of the workers by using Casella personal air samplers. Average respirable asbestos fibre concentrations at the workplaces were from 0.06 fibre/cm3 (control desk operator) to 2.25 fibre/cm3 (spinning machine operator), and the average total dust concentrations were from 0.7 mg/m3 (technicians) to 2.3 mg/m3 (preparatory department workers). Compared with the 1980-1985 period, total dust concentrations were 1.5 times, and respirable asbestos fibre concentrations 2.9 times lower. Considering the obtained data and the analysis of the occupational diseases in workers exposed to asbestos dust during 1983-1988, the national expert group for industrial dusts has suggested that the MAC values for chrysotile dusts be lowered to 1.0 mg/m3 (total dust) and 0.5 fibre/cm3 (respirable fibre).