<prompt> Pneumoconiosis is caused due to inhalation of dust within the size range of -0.5-2.5 microns3-6 microns6.5-8 microns10-20 microns  <response>: Paicle size of air contaminants must be considered in pneumoconiosis .Paicles 10-15 microns do not penetrate beyond the nose and throat.Paicles 2.5-10 microns contain crustal elements such as silica,aluminium,and iron.These paicles mostly deposit high in the tracheobronchial tree.Fine -mode fraction include paicles less than 2.5 microns,which are carried to the lower airways and produces pneumoconiosis. Reference:Harrisons medicine-18th edition,page no:2122. 