Fibrosis and scarring of the lungs secondary to the repeated inhalation of dust associated with some occupation. Examples include silica, asbestos and coal dust exposure. Occupational Lung Diseases are a branch of occupational diseases concerned primarily with work related exposures to harmful substances, be they dusts or gases, and the subsequent pulmonary disorders that may occur as a result. Substances known to cause lung disease include coal dust, Asbestos, crystalline silica, a form of Silicon dioxide (which is usually in the form of quartz) and Barium. In Certain Industries, especially those involving grinding or stone-breaking or glass industries, so much dust is produced that the defense mechanism of body cannot fully cope with the situation. Long exposure can give rise to inflammation leading to fibrosis (proliferation of fibrous tissues) and thus causing serious lung damage. Workers in such industries should wear protective mask. (An OSH glossary used in safety and health at work which is, adopted by ILO {102}.. The term definition has been obtained from the secondary source