Types of Dusts and their Effects: Dust is a disperse system (aerosol) of solid small particles in air or gas whose size distribution is like a colloid. It originates from mechanical communication of coarser material. Mining, breaking, crushing, grinding, mixing, polishing and handling are the main dust generating processes. Small particles of 0.1 to 5 u.m. size (respirable dust) can remain in the alveolar passages of which smaller particles (O.I r-lm) behave as colloids or smoke, deposit in lungs and other parts and cause health effect. Particles or larger size (>5 (im) are driven back by the clearance mechanism. Asbestos fibre of 3 (urn or less in diameter and upto 100 (in length can reach the alveoli, while the smallest fibres can reach upto pluera and pluera space. 2nd Schedule of the Factories Act prescribes TLV (permissible time-weighted average i.e. TWA concentration per 8 hours) of cotton, asbestos, coal, cement and silica dusts. Types...