1) The method must determine the exposure of employees by sampling in the breathing zone of the employee exposed.

2) 'Fibre' means a particle with a length > 5 µm, an average diameter < 3 µm, and a ratio of length to diameter > 3 to 1, which can be seen using the system specified in paragraph 3.

3) Fibres shall be counted in accordance with AIA RTM1.

4) The results shall be regularly tested by quality assurance procedures to ensure that the results are in satisfactory agreement with the average of results, obtained by approved inspection authorities (AIA) participating in a national quality assurance scheme, using the method specified in paragraphs 1 to 3 above.