This method is used to determine fibre structures in deposited dust on surfaces. An assignment of the fibres to certain substance classes (e.g. chrysotile, amphibole asbestos, AMF, other inorganic fibres) is easily possible with the help of the EDX analysis in the scanning electron microscope. According to VDI 3492, this method must not be used to assess indoor air pollution. Furthermore, according to VDI 3866, it is not suitable for determining the asbestos content in (technical) products.
Sampling is uncomplicated. It is performed by means of an adhesive tape or a carbon pad (conductive tabs). A particularly simple and reliable sampling is achieved with the help of our sampling set (PHOTO adhesive sampling box).
The test substrate is now pressed onto the surface once (at least 1 cm² of the test substrate surface). Smooth surfaces are particularly suitable. Depending on the floor area of the room to be sampled, the number of samples must be determined:
|area [m²]||Minimum number of samples|
|30 – 100||5|
|100 – 500||7|
|500 – 1000||10|
|> 1000||> 10|
After pressing on, carefully remove the sampling medium again and transfer it to a transport container. Care should be taken to ensure that there is no contact between the sampled side of the medium and the transport container during transport. Before sending, the sample should also be labelled in a meaningful way (e.g. place of collection).
The evaluation takes place in the scanning electron microscope. As soon as a fibre is detected, it is clearly identified and classified by means of an EDX spectrum. The evaluation is carried out in two counts, in each of which a specific area is searched.
If the boundary conditions are observed, a detection limit of approx. 40 fibres per cm² surface is achieved. The evaluation of the results is carried out according to a semi-quantitative scheme:
|Weighted count result ZW [cm-2]||Surface load|
|0||No fibre type detected|
|1 – 100||Fibre type detected|
|101 – 500||Surface significantly loaded with fibre type|
|> 500||Surface heavily loaded with fibre type|
(Fibre type stands for asbestos, artificial mineral fibres or other inorganic fibres)