Crystalline Silica Fact Sheet
Silica, one of the most common compounds on earth, is made of oxygen and silicon. Most soils and rocks contain some percentage of silica. The sandstone hills and bluffs of western Wisconsin and southeastern Minnesota contain almost 100 percent silica, also called crystalline silica sand and quartz sand. The high percentage of silica sand in the sandstone deposits and the nearness to the surface of the earth make them attractive to mining companies for use as frac sand.
Many crystalline silica particles combine to form a grain of silica sand. Some of these particles are also found loose in the cementing material that holds all the grains of sand together in a sandstone formation (hill or bluff). When sandstone is mined, the free particles from this cementing material are released. If any of the grains of sand are shattered/crushed, this will also produce crystalline silica particles.
All particles of a breathable size are harmful to health. Particles in the air are called particulate matter. Particles can come from diesel exhaust, gasses, volatile organic compounds, dust, and many other sources. Crystalline silica particles of a breathable size are especially harmful because they have sharp edges. Once inhaled into the lungs, they cannot be expelled. Their continuous presence in the lungs can cause scarring of the lung tissue. If small enough, they may also pass through the lungs and enter the bloodstream.
Large scale and widespread sand mining is expected to increase the amount of all particles in the air, including particles of crystalline silica. In the case of sand mining, these particles are often called silica dust. If this dust is not captured by dust control devices, it is called fugitive dust.
Exposure to unsafe levels of Particulate Matter of any kind is known to cause increased respiratory symptoms such as irritation of the airways, coughing, difficulty breathing, decreased lung function, aggravated asthma, development of chronic bronchitis, irregular heartbeat, nonfatal heart attacks, premature death in people with heart or lung disease, and cancer. Exposure to high levels of respirable crystalline silica over a short period or lesser levels over a longer period can lead to silicosis. Some studies also show increases in autoimmune diseases with exposure to unsafe levels of respirable crystalline silica.
When issuing Air Quality Permits to mining companies, the Department of Natural Resources does not include fugitive dust when determining how much the companies will increase the level of particulate matter. They also do not regularly require air monitors for either general particulate matter or, specifically, for respirable crystalline silica. Therefore, people living anywhere near mining operations do not know whether they are breathing safe or unsafe air.