<prompt> Respirable dust, responsible for pneumoconiosis, has a size limit of:1 micron5 micron10 micron100 micron  <response>: Pneumoconiosis occur due to occupational exposure to dust. Paicles size 0.5 to 3.0 microns are the most dangerous as a health hazard causing pneumoconiosis, as they reach the interior of lungs with ease. Paicles size and behaviour: Paicle size Behaviour 10 microns Settle down by gravity 10 microns Remain suspended in air 5-10 microns Arrested in upper respiratory tract 3-5 microns Deposited in mid respiratory tract 1-3 microns Enter alveoli and settle there cause pneumoconiosis 1 more Brownian movement Ref: Park 25th edition Pgno: 843 