BS ISO 13794:1999

1   Scope

 1.1   Substance determined 
 This International Standard specifies a reference method using transmission electron microscopy (TEM) for determination of the concentration of  asbestos  structures  in ambient atmospheres. The specimen preparation procedure incorporates ashing and dispersion of the collected particulate, so that all  asbestos  is measured, including the  asbestos  originally incorporated in particle aggregates or particles of composite materials. The lengths, widths and  aspect ratios  of the  asbestos  fibres  and bundles are measured, and these, together with the density of the type of  asbestos , also allow the total mass concentration of airborne  asbestos  to be calculated. The method allows determination of the type(s) of  asbestos  fibre  present. The method cannot discriminate between individual  fibres  of the  asbestos  and non- asbestos  analogues of the same  amphibole  mineral.