Silica dust exposure is a significant hazard in rock mining, whether it be a granite vein in a coal, copper, or diamond mine, or other rock cutting activities (granite cutting, stone dust facilities, etc.). It can also be a problem in the oil & gas industry due to the silica sand used in hydraulic fracturing. Lung cancer, silicosis, and chronic obstructive pulmonary disease can result from exposure to silica dust, so it is important to have appropriate personal and area dust monitoring equipment in place to limit exposure. Silica is usually monitored by collecting a total dust sample, which would include silica as well as coal dust and diesel particulate, and sending it to a laboratory for analysis, typically using X-ray diffraction (XRD) techniques.
The Occupational Safety and Health Administration (OSHA) website describes the process for collecting an air sample to measure airborne silica as follows:
A trained specialist, such as a certified industrial hygienist, will use a combination device called a cyclone assembly and a sampling pump to trap tiny respirable silica particles from the air in the work environment.
- The cyclone assembly and sampling pump will be placed on an employee, who will wear the device throughout the work shift for up to 8 hours.
- All employees may be fitted with the sampling device or just a select few who are closest to the silica source may be fitted. The industrial hygienist can help you determine what will be most appropriate.
- The hygienist will return at the end of the sampling period to de-activate the sampling pump and remove the filters to be sent for analysis.
OSHA determined that employees exposed to respirable crystalline silica at the previous permissible exposure limits face a significant health risks and amended its existing standards. OSHA’s Final Rule to Protect Workers from Exposure to Respirable Crystalline Silica offers two standards, one for Construction and one for General Industry and Maritime, and makes the following provisions:
- Reduces the permissible exposure limit (PEL) for respirable crystalline silica to 50 micrograms per cubic meter of air, averaged over an 8-hour shift.
- Requires employers to: use engineering controls (such as water or ventilation) to limit worker exposure to the PEL; provide respirators when engineering controls cannot adequately limit exposure; limit worker access to high exposure areas; develop a written exposure control plan, offer medical exams to highly exposed workers, and train workers on silica risks and how to limit exposures.
- Provides medical exams to monitor highly exposed workers and gives them information about their lung health.
- Provides flexibility to help employers — especially small businesses — protect workers from silica exposure
Both standards contained in the final rule take effect on June 23, 2016, after which industries have one to five years to comply with most requirements, based on the following schedule:
Construction – September 23, 2017
General Industry and Maritime – June 23, 2018
Hydraulic Fracturing – June 23, 2018 (Engineering Controls- June 23, 2021).
To learn more about global air quality regulations and solutions for successfully complying with those regulations, visit the Air Quality Analysis Information page in the Thermo Fisher Scientific Environmental Learning Center.