The use of scanning electron microscopy (SEM) and energy dispersiveX-ray analysis (EDXA) as a measurement tool for EMPs tasks, guidelines

Abstract

In a variety of European countries SEM/EDXA based methods are widely used for the measurements and judgements relating thereof regarding asbestos analysis. Most of these methods are used also for other fibrous particles, commonly indicated as Elongate Mineral Particles (EMPs).The span of guidelines reflects the broad use of SEM/EDXA as an analytical method. Guidelines regarding air measurements both for ambient and indoor air are well established. These methods are widely used as is shown in a proficiency testing scheme, organized by the British Health and Safety Executive (HSL) with participants from countries all over Europe and some countries from Asia and Africa. For workplaces a similar guideline with a reduced sensitivity is available, allowing measurements in higher dust concentrations. Features of the methods like analytical sensitivity, detection limits and measurement uncertainty are discussed.For material analysis we apply different analytical methods, using SEM/EDXA as a final step. They are different both in sample preparation and sensitivity. Most of the methods are qualitative or “semi-quantitative” and thought for the analysis of commercial asbestos containing products mainly. If quantitative analysis based on EDXA is used for identification other EMPs can be identified as well. An important tool is the morphological impression of the fibers or structures in the SEM in addition.Changes in regulations which may be expected, will modify some of the methods. Especially lowered Threshold Limit Values (TLV's) in occupational air measurements are difficult to achieve.