The Dangers of Silica Exposure
What is silicosis?
Silicosis is a disease of the lungs caused primarily by the breathing of dust containing crystalline silica particles. This dust can cause fibrosis or scar tissue formations in the lungs that reduce the lung’s ability to work to extract oxygen from the air. There is no cure for this disease, thus, prevention is the only answer.
Why it’s deadly
You can be in danger even if you don’t see the dust. When you breathe dust that contains silica, the tiny particles may damage your lungs. Silicosis can form in your lungs in as little as a few weeks of very high dust exposure. Even breathing small amounts over time can cause disease years later. By the time it gets hard to breathe, you are already sick and there is no cure for silicosis. Silica dust may also cause lung cancer or increase your chance of getting tuberculosis – and it has been linked to COPD and other illnesses.
The good news is that silicosis is preventable! When using power tools, the use of dust attachments, HEPA dust extraction and respiration equipment are critical to helping reduce silica exposure.
Ensure jobsite compliance
Following the September, 2017 enforcement date (and subsequent grace period) and depending on the other State and local regulations, OSHA has now fully-implemented a final rule to help curb lung cancer, silicosis, chronic obstructive pulmonary disease and kidney disease in America’s workers as related to silica dust by eliminating their exposure to respirable crystalline silica. Since then, OSHA has released a number of updates to provide guidance and clarification.
- 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.
Employers can use control methods that reduce the exposure below the PEL by following an OSHA-specified exposure control method (see Table 1 below), measuring workers’ exposure to silica independently, or using objective data sufficient to accurately characterize employee exposures to respirable crystalline silica (Section (d)(2)(ii). Regardless of which control methods are used, all construction employers covered by the standard are required to:
- Establish and implement a written exposure plan and designate a competent person to implement the plan
- Restrict housekeeping practices that expose workers to silica
- Offer medical exams every three years for workers who wear a respirator 30 or more days per year
- Train workers on operations that result in silica exposure
- Keep records of workers’ silica exposure and medical exams
Addtional information on dust control methods
Vacuum Dust Collection System (VDCS)
Commercially available VDCSs have been shown to reduce silica exposures. The VDCS must include a:
- Hood or shroud that is recommended by the tool manufacturer.
- Vacuum that is recommended by the tool manufacturer with enough suction to capture dust at the cutting point.
- Filter with a 99 percent or greater efficiency in the vacuum exhaust and a filter cleaning mechanism.
- Vacuum exhaust hose capable of providing the airflow recommended by the tool manufacturer.
Commercially available VDCSs have been shown to reduce silica exposures. Proper operation includes:
- Keeping the vacuum hose clear and free of debris, kinks and tight bends.
- Turning the vacuum off and on regularly to reduce dust buildup on the filter, if it is not self-cleaning.
- Changing vacuum-collection bags as needed or at least as often as recommended by the manufacturer.
- Avoiding exposure to dust when changing vacuum bags and cleaning or replacing air filters.
- Setting a regular schedule for maintenance as recommended by the manufacturer.
Housekeeping Methods in October, 2017, OSHA communicated interim enforcement guidance which also clarified the use of sweeping compounds (e.g., non-grit, oil- or wax-based) as an acceptable dust suppression housekeeping method.
Note on wet cutting
Operating tools and machines with integrated water delivery systems (wet cutting) may produce slurry that can present additional hazards not covered in the Silica Rule. The use of specialized slurry vacs or other methods of consolidation are recommended. See an Associate for details.
Where water is used to control dust, electrical safety is a particular concern. Use ground-fault circuit interrupters (GFCIs) and watertight, sealable electrical connectors for electric tools and equipment on construction sites.
Indoors or in enclosed spaces
Using wet methods or a VDCS indoors or in an enclosed area may not reliably keep exposure low, so extra ventilation may be needed to reduce visible airborne dust. Extra ventilation can be supplied by using:
Ensure air flow is not impeded by the movements of employees during work, or by the opening or closing of doors and windows. Position the ventilation to move contaminated air away from the workers’ breathing zones.