An (ash cloud) may contain levels of silica.Logical formLearned from2 sentences. Silica can be a component.Logical formLearned from2 sentences. Contaminants may be trapped in crust of silica.Logical formLearned from2 sentences. Concentration of silica can be a discovery.Logical formLearned from2 sentences. A silica can be (surface coating).Logical formLearned from2 sentences. A silica can be prepared.Logical formLearned from2 sentences. Boxes can be constituted-of-or-filled-with (silica mud).Logical formLearned from2 sentences. Silica can be in supply.Logical formLearned from2 sentences. A respiratory disease may be caused by exposure to silica.Logical formLearned from2 sentences. Illness can be from silica.Logical formLearned from2 sentences. (Silica cases) can be legitimate.Logical formLearned from2 sentences. Some silica can be in some cases.Logical formLearned from2 sentences. An injury can be from silica.Logical formLearned from2 sentences. Victims can be constituted-of-or-filled-with (silica exposure).Logical formLearned from2 sentences. A silica may replace cells of a wood.Logical formLearned from2 sentences.