[27][28] This effect can create an occupational hazard for people working with
sandblasting equipment, products that contain powdered crystalline silica and so on. Children, asthmatics of any age, allergy sufferers, and the elderly (all of whom have reduced lung capacity) can be affected in much less time. Amorphous silica, such as fumed silica is not associated with development of silicosis, but may cause irreversible lung damage in some cases.
[29] Laws restricting silica exposure
with respect to the silicosis hazard specify that they are concerned only with silica that is both crystalline and dust-forming.