规定了使用透射电子显微镜测定周围大气中石棉结构物浓度的参考方法，包括测量石棉结构物的长度、宽度和长径比。该方法允许测定存在的石棉纤维类型。该方法不能区分同一角闪石矿物的石棉和非石棉类似物的单个纤维。

Specifies a reference method using transmission electron microscopy for the determination of the concentration of asbestos structures in ambient atmospheres and includes measurement of the lengths, widths and aspect ratios of the asbestos structures. The method allows determination of the types of asbestos fibres present. The method cannot discriminate between individual fibres of the asbestos and non-asbestos analogues of the same amphibole mineral.