“…Although the mechanism of the diseases is still not completely elucidated, causality for silica, asbestos and coal dust is demonstrated by post mortem pathohistological evaluation of lung tissue for silicosis, asbestosis and coalworker pneumoconiosis (Ndlovu et al, 2017;Ndlovu et al, 2016;Nelson et al, 2010;Naidoo et al, 2005;Corbett et al, 1999;Hnizdo et al, 1993;Nelson et al, 2011;Murray et al, 1996). The presence of slate-grey to dense black silica dust-laden macrophages (sometimes visible silicate crystals), asbestos fibres and asbestos bodies and pigment-laden macrophages, and anthracitic pigmentation (coal dust) are evidence for exposure, but they are not sufficient for the diagnosis of pneumoconiosis (Landrigan, 2016). On the other hand, the absence of these lesions does not exclude a diagnosis of pneumoconiosis (Landrigan, 2016).…”