Measurement of the asbestos dust concentration in air. Description and limits of the methods.

Since the beginning of this century a wide range of methods were used to evaluate the asbestos exposure of workers. Instruments such as the konimeter, thermal precipitator impinger or tyndallometer were employed to collect dust samples. Currently, the membrane filter method associated with phase contrast optical microscopy is widely accepted These different sampling method are presented in this paper and the relationships between asbestos concentration recorded by means of methods used in the past and with the current membrane filter method or with direct-reading instruments are discussed. Emphasis is put on the difficult to use such relationships which were often established for specific situations (in the mine industry for instance). For non occupational exposure the use of electron microscopy methods is evaluated.