Amorphous silica vs. Crystalline silica
Silica molecules can combine into different forms. Two of these forms are amorphous silica, and crystalline silica. While these are both forms of silica, they have different properties and different health effects. Amorphous silica can cause irritation of the lungs and respiratory tract, and may cause lung scarring. It is less hazardous than crystalline silica. Examples of amorphous silica include glass, diatomaceous earth, silica fume and silica gel. Exposure to respirable crystalline silica can cause serious health effects such as silicosis and lung cancer, which are both irreversible and potentially fatal.
Amorphous silica and crystalline silica are treated separately in the Health, Safety and Reclamation Code for Mines in British Columbia (HSRC) and have different occupational exposure limits. Crystalline silica is the form that is most common on mines. Although exposure to amorphous silica can also occur at mine sites, the Silica Control ToolTM is designed to be used for crystalline silica only.