What Is Silica?

NIOSH defines silica as the compound silicon dioxide. Crystalline silica forms when its molecules arrange into crystalline form, and respirable crystalline silica refers to particles containing crystalline silica that are small enough to inhale deep into the lungs. NIOSH says crystalline silica is typically found in soil, sand, concrete, brick and cement, mortar and plaster, granite and other rock and stone, and engineered, or artificial, stone.

The danger is the dust. NIOSH says silicosis is a lung disease caused by inhaling excessive amounts of respirable crystalline silica, that it is not reversible but is preventable, and that excessive exposure can also cause lung cancer, chronic obstructive pulmonary disease, certain autoimmune diseases and chronic renal failure.

At work, OSHA's respirable crystalline silica standards bar employers from exposing any employee to more than 50 micrograms per cubic meter of air as an 8-hour time-weighted average. The general industry standard took effect June 23, 2016, with most obligations starting June 23, 2018, and the construction standard took effect the same day, with nearly all obligations starting June 23, 2017.