Crystalline silica is a common mineral found in the earth's crust. Materials like sand, stone, concrete and mortar contain crystalline silica. It is also used to make products such as glass, pottery, ceramics, bricks and artificial stone.
Respirable crystalline silica – very small dust particles at least 100 times smaller than ordinary sand you might find on beaches and playgrounds – is created when cutting, sawing, grinding, drilling, and crushing stone, rock, concrete, brick, block and mortar.
When airborne, these dust particles, mostly 10 micrometers in size and smaller, are too small to see, but can be inhaled deep into the lungs where they can cause damage. The smaller the crystalline silica particles, the greater the risk.
The following are examples of activities at the UW that may include risks of exposure to respirable crystalline silica:
- Jack hammering
- Asphalt mixing
- Rock drilling, cutting, chipping or polishing
- Brick or tile cutting and sawing
- Stone (natural and artificial) countertop fabrication
- Concrete drilling, sawing, grinding and polishing
- Work with pottery, ceramics and glass
Health effects from respirable crystalline silica exposure
Breathing silica dust can cause many acute and chronic diseases. Workers can breathe in harmful amounts of silica dust over time and eventually develop a disabling lung disease (e.g., silicosis or lung cancer) when effective dust control measures are not used. Over time, the crystalline silica causes scarring of the lungs, impairing the lungs' gas exchange ability. Silicosis is caused by inhalation and deposition of respirable crystalline silica particles less than 10 micrometers in diameter.
Respirable crystalline silica exposure has also been linked to chronic obstructive pulmonary disease (COPD), kidney and auto-immune diseases, increased risk of latent tuberculosis (TB) infection and other lung infections.
The best way to prevent diseases associated with respirable crystalline silica exposure is to control the exposure to silica dust. Exposure controls include engineering controls, wet methods, specific work practices and personal protective equipment (PPE).
Specific exposure control methods
Prior to commencing work with or disturbing crystalline silica, a Crystalline Silica Exposure Control Work Plan must be completed.
An exposure assessment including air monitoring may be required to determine appropriate exposure control methods.
Washington state, in WAC 296-840-110 Table 1, has identified specific equipment and tasks involving the disturbance of crystalline-silica and assigned each required engineering controls and a minimum respiratory protection factor.
The specified respiratory protection requirements are task-time dependent in two categories, less than or equal to four hours, and greater than four hours. When performing tasks which are indistinguishable than those described in Table 1 from WAC 296-840-110, an exposure assessment is not required. The engineering controls, work practices, and respiratory protection must be properly and fully implemented when performing work outlined in Table 1.
The Respirable Crystalline Silica Safety Manual outlines the responsibilities of University units, personnel and EH&S to protect University personnel from occupational respirable crystalline silica exposure. This document also contains guidelines and procedures for exposure control, respiratory protection, and medical evaluations.
To request exposure monitoring for employees working with or disturbing crystalline silica, please contact EH&S for scheduling prior to performing the work.