Document gDe7RkOBqkOJy5eB51B5YO3VL

- 52 1.2. Outdoors at several sites Table V-3. Average chrysotile asbestos concentrations at several sites In 10 ^g/n^ location U.K. Rickards (1971, 1973) Netherlands U.E.R. CSSR France 3.G. TNO Nlckelson Simecok Bignon (1976) (1970) (3971) et al Munchio (3975) (1973) Germany RobOck (1973) At the site of an asbestos pro cessing Industry, down wind 1 100* *4 u 1000 u u Town center 0.1 < 0.1 75 - 60 u 0.7-3.5 <0.) Industrial area 0.1 O 45 - 300 u u u Aural area 0.3-1 u 70 uu I) u i unKxiC-v/n * Down wind, at a height of 1.5 m, ISO m from an nsl-vftos processing industry * Down wind, at a height of 2 m, 300 n from an asbestos processing industry *** Personal communication: measurements have been carried out by CEkCHAR-France in Essen. Fibres were found but no asbestos. Botelle (Frankfort) found fibres In Frankfurt with optical microscopy; a frac tion of these fibres had properties resembling those of asbestos. This would result in a concentration of Approximate!y 100 x 10-9g/m3 . Apart frer. what has been jointed out in the beginning of this chapter on the ccmparison of the results of different tnvoctigators, it should also be kept In mind that the practical detection- limits^ asbestos in air, using electron microscopy as an analytical tool Mes *-weorh 10 ^ and 30 g/ro . It should be noted that the majority of fibres detected in the prelimi nary Dutch investigations, sec Table 3, had a diameter of approximately 0.02 pm end a length of approximately 0.5 pm, which means that they could only be detected with the aid of an electron microscope. These results are - I I as Fin Fescon men pro cle vir 2. U\ co> a. b. U. 3. <1 0?<<5 produced by ford