Dusts are solid particles generated by handling, crushing, grinding and disintegrating organic or inorganic materials, such as rocks, ore, metals, coal, wood and grains. The exposure of man to dusts can lead to a variety of respiratory diseases, including pulmonary fibrosis, obstructive lung disease, allergy and lung cancer. Toxic dusts may produce systemic poisoning after inhalation, or act as skin irritants to produce dermatoses, allergic reactions or cancer.