Dust inhalation lung disorder. Light micrograph of a section through lung tissue from a pnemoconiosis patient, with clumps (black) of dust particles. The individual particles have to be below 0.005 millimetres in diameter to penetrate deep into the lungs. They eventually cause breathlessness as the healthy tissue degenerates into fibrous masses. Most cases are due to industrial exposure to coal dust, silica and asbestos. Treatment is palliative (reducing the impact of the symptoms) and there is no cure. Magnification unknown.