Because of its many positive technical properties, asbestos was widely used in Germany, with some exceptions, until the ban on asbestos in 1979. A general ban has been in place in Germany since 1993 and in the European Union since 2005.
Asbestos was used in high concentrations, up to 100 %, for heat, fire or sound insulation tasks where no significant static requirements were made, e.g. as sprayed asbestos, sealants, cardboard or cords.
For the reinforcement of materials, to improve fracture and bending behaviour, as e.g. in asbestos cement, or to increase elasticity and/or viscosity, as e.g. in paints, adhesives, sealants or road surfacing, asbestos was added in low contents of more than 1 % by mass.
In only a few exceptions, such as some adhesives, sealants or fillers, the asbestos mass percentage can be as low as 0,4 %.
This method describes the procedure for taking material samples, sample processing and analytical detection of technically relevant asbestos such as chrysotile (white asbestos), crocidolite (blue asbestos) and amosite (brown asbestos) up to a detection limit of approx. 1 mass percent. It cannot be used to detect or exclude asbestos at trace levels such as contamination or in natural mineral raw materials or applications. For this purpose, other methods such as BGIA method 7487 or VDI 3866 with corresponding concentration must be used.
According to the GefStoffV (Hazardous Substances Ordinance), the handling of asbestos is prohibited. However, demolition, renovation and maintenance work as well as the necessary ancillary work and research work are exempt from this ban. These ancillary activities also include the taking of material samples and their examination in the laboratory. Since fibre releases may occur during sampling, special care is required. If the following handling instructions are observed, it can be assumed that fibre release will be avoided. If this cannot be guaranteed in exceptional cases, further technical measures must be taken, e.g. point extraction, partitioning or negative pressure, to prevent the fibres from spreading.
If a drill is used to sample material from deeper layers, make sure that it runs slowly and only produces coarse chips. Tools used must comply with the requirements of TRGS 519.
Samples shall be taken in the following manner:
- the sampling point is moistened by means of a spray bottle, a water-soaked brush or a damp paper towel.
- a piece of the material to be sampled with an area smaller than 1 cm2 in the case of thin materials or a volume smaller than 1 cm3 in the case of materials several centimetres thick is removed by breaking it off with pliers or by cutting it off with a sharp cutting tool.
- the samples are deposited individually in a dust-tight container and clearly labelled.
- the sampling site and the immediate surroundings are wiped with a damp cloth.
- the exposed surface is resealed with a dab of paint or adhesive.
Only a small sample amount of a few milligrams is needed for the analytical procedures. The sample is glued onto a conductive tab and thinly coated with gold for further analysis in the SEM.
If asbestos is found, the corresponding two-dimensional fibre area percentage is put in relation to the corresponding non-fibrous particle areas. Since an exact percentage estimation is not possible, only an estimation into the following classes is made:
n.n. = asbestos not detected
Traces = traces of asbestos detected
1-5 = asbestos mass fraction ca. 1 % to 5 %
5-20 = asbestos mass fraction ca. 5 % to 20 %
20-50 = asbestos mass fraction ca. 20 % to 50 %
>50 = asbestos mass fraction over 50 %
The detection limit for the method VDI 3866 sheet 5 is a mass fraction of 1 %.
One possibility to lower the detection limit of the method is available for those materials where the asbestos content can be concentrated by means of an extended preparation such as acid treatment or hot ashing (see VDI 3866 Sheet 5, Appendix B) and / or a larger sample area is searched. According to Annex B of VDI 3866 Sheet 5, taking into account the reference fibres specified there, the detection limit for such samples is 0.001 % mass fraction of asbestos or respirable artificial mineral fibres.
