[International control of the quality of microscopic-numerical analysis of the levels of man-made mineral fibers (MMMF) in the air of the work area].

In the years 1986-1990 the Institute of Occupational Medicine in Lodz (Department of Aerosols) participated in seven exchanges of preparations within the WHO/Euro MMMF Reference Scheme programme. The number of persons analysing the preparations increased from three, during the first exchange, to seven in the sixth. Markings in the 1st and 3rd exchange constituted two thirds of the reference markings. In the 2nd, 5th and 7th exchange the markings were similar, and in the 6th exchange they were lower than in the reference markings. According to the accepted system, the markings of the standardized density in four exchanges (2nd, 5th, 6th and 7th) were determined as class I (0.70-1.40), and in the remaining exchanges (1st, 3rd and 4th) of class II (0.50-2.00).