A Contractor’s Guide to Silica
In 2016 the Occupational Safety & Health Administration (OSHA) published updated rules meant to protect employees from exposure to respirable crystalline silica (to keep things simple, we’ll just refer to it as silica in this article). This guide is intended to provide information about silica hazards and clarify the silica standard for contractors–OSHA has separate rules for general industry or maritime work.
What is silica and why should I care?Silica is a chemical compound commonly found in sand, stone, concrete, brick, mortar and other materials. When left undisturbed, silica does not present a hazard. However, once disturbed (through activities such as concrete cutting or sandblasting) the silica becomes a fine, easily inhaled dust that is hazardous if inhaled.
Tiny silica particles lodge themselves in the lungs where they cause disabling (and sometimes fatal) lung diseases such as lung cancer and silicosis, as well as kidney disease and chronic obstructive pulmonary disease. That’s bad news for unprotected employees who are exposed to silica.
I want to protect my employees! What do I need to know?OSHA has published a standard that governs occupational exposure to silica. The permissible exposure limit (PEL) for silica, as of 2016, is 50 micrograms of respirable crystalline silica per cubic meter of air (µg/m3), averaged over an eight-hour day. That’s a big change from the pre-2016 PEL of 98 µg/m3 (100% quartz), but the newer limit is based on updated science that shows even small amounts of silica exposure can be harmful to health.
The standard also comes with an “action level” of 25 µg/m3—if your employees are exposed to 25 µg/m3 of silica or more in the air, you need to develop an exposure control program and demonstrate what you’re doing to reduce employee exposure.
How do I know if my employees are exposed above the PEL? Do I need to test?If you’re doing any of the following tasks, your employees may be exposed above the PEL and you should be taking measures to reduce their exposure:
- Drilling, grinding or cutting concrete or stone
- Setting duct and pipe hangers into concrete
- Using jackhammers or powered chipping tools
- Crushing concrete or stone
- Demolition of concrete or silica-containing materials
- Sanding drywall
To know the exact exposure levels, you would need to conduct respirable crystalline silica exposure monitoring for each silica-related task. This involves a sampling pump being attached to your employee. The pump pulls in air, collecting respirable crystalline silica on a filter throughout the shift. Then the filter is analyzed to determine the amount of silica the employee is exposed to.
To help make things easier for small contractors, OSHA has created a table featuring common tasks that have silica exposures. For each listed task, they have identified the hazard control methods (engineering controls, work practices and respiratory protection) you should be using to protect employees. If your employees are only doing the tasks listed in the table AND you are already doing the hazard control methods identified there, then there is no need to conduct employee exposure monitoring.
When is monitoring required for contractors?Silica exposure monitoring is only required for situations where:
- Your employees are doing a task not listed in OSHA’s table
- You are not fully and properly implementing the engineering controls, work practices and respiratory protection described in the table
So what’s my plan of action for making sure I’m in compliance with the standard and protecting my employees from silica exposure?
- Identify tasks that might expose employees to silica. You’ll need to identify a competent person as well. This is someone who is capable of identifying silica hazards and who is authorized to take prompt corrective measures to control or eliminate those hazards.
- Compare your task list to OSHA’s table. For each task listed, make sure you’re following the control methods shown, including engineering controls (such as wet cutting or exhaust ventilation), work practices (like wetting down dust before cleaning it up) and respiratory protection. Note that using respirators to protect employees is only allowed when engineering and work practice controls are being used but can’t keep exposures at or below the PEL.
- For tasks not listed in the table, you’ll need to conduct exposure monitoring (that complies with OSHA’s methods of sample analysis) and come up with a program for how you will control employee exposure. Highly exposed employees (those required to wear a respirator for 30 or more days per year) may need medical exams that include chest X-rays and lung function tests.
- Create a written exposure control plan. This doesn’t have to be complicated. Create a document listing the tasks you identified, the control measures and housekeeping practices you are using to protect workers, and procedures you are using to restrict access to silica work areas.
- Train your employees to understand what work operations result in silica exposure. Make sure they understand how to limit their exposure.
- Keep records of any monitoring and medical exams.
Are there any unexpected jobs that might present a silica exposure?Cleaning up dust is a common one. Wet cutting and grinding methods do a great job of controlling silica dust, but even they generate some material that will have to be cleaned up once it’s dry. Removing with a broom creates a cloud of dust—the opposite of what you want to do. Even if you add a sweeping compound to make the material clump up, you’re still going to have some airborne silica. Instead, we recommend that you remove silica-containing dusts with a HEPA filtered vacuum. Never use compressed air to clean up silica-containing dust.
Another recently recognized silica hazard is present in natural or manufactured stone countertops. These materials all contain silica in varying amounts, but engineered stone is especially hazardous because it contains substantially more silica than natural stone (over 90 percent silica, compared with less than 45 percent in granite). Engineered stone has become increasingly popular, expanding the numbers of employees who are exposed during manufacture, finishing and installing. Many tasks in the stone fabrication and installation industry have been linked with hazardous silica exposure, including:
- Cutting, grinding, polishing
Control measures for this industry are like those recommended for other silica exposures: tools equipped with water feeds and well-designed local exhaust ventilation, and, when needed, appropriate respiratory protection.
Are there any jobs the silica standard does not apply to?OSHA’s silica standard for construction does not impact tasks where the hazard exposure will stay low under any foreseeable conditions. This includes tasks like mixing mortar, pouring concrete footers or slab foundations, or removing concrete forms.
Find More Online