Crystalline silica is one of the most persistent hazards encountered at work, with 2.3 million American workers exposed to it yearly. A common mineral, crystalline silica is regularly found in stone, soil, and sand throughout the earth. This means that it’s also found in many ubiquitous construction materials, like concrete, bricks, glass, and mortar, as well as pottery, ceramics, and artificial stone. Silica is generally not hazardous in these materials.

When silica becomes airborne, however, it can be extremely dangerous to workers. Airborne crystalline silica particles, 100 times smaller than ordinary sand, are respirable. These miniscule particles are created and released into the air during industrial activity, which can include the following.

• Cutting or crushing stone
• Sanding or drilling into concrete
• Sawing brick or concrete
• Abrasive blasting with sand
• Grinding mortar
• Manufacturing glass, brick, metal molds, concrete blocks, stone countertops, or ceramics
• Using industrial sand in foundry work or hydraulic fracking

When inhaled, silica can damage lung tissue, potentially leading to numerous health problems such as lung cancer, chronic obstructive pulmonary disease (COPD), kidney disease, and silicosis. This is an interstitial lung disease (ILD) in which silica particles cause inflammation and permanent lung scarring, or pulmonary fibrosis. Silicosis is incurable and can cause other major complications like tuberculosis, lung cancer, chronic bronchitis, autoimmune disorders, and kidney disease. Preventing or limiting exposure to silica particles is the way to limit worker risk, and this is where OSHA’s Respirable Crystalline Silica Standard comes in.

OSHA’s Respirable Silica Standards

The Occupational Safety and Health Administration (OSHA) has two standards requiring employers to limit employee exposure to respirable crystalline silica, one for Construction and one for General Industry and Maritime. 

General Industry and Maritime Standard

Workplaces outside of the construction industry follow a standard set of guidelines. Under these, employers must:

• assess employee exposure to silica at or above the action level of 25 µg/m³ (micrograms per cubic meter of air) over an 8-hour workday.
• prevent employee silica exposure above the Permissible Exposure Level (PEL) of 50 µg/m³ over an 8-hour workday. This must be done by:

               ○ limiting worker access to areas with potential exposure above the PEL.

               ○ using dust controls to protect workers from exposure above the PEL.

               ○ providing respirators when dust controls aren’t sufficient.

               ○ using housekeeping methods that don’t create airborne dust.

• establish and implement a written exposure control plan identifying steps to protect employees during specific hazardous tasks.
• offer medical exams every three years for workers exposed at or above the action level for 30 days or more per year.
• keep records of exposure data and measurements, as well as medical exams.
• train workers on which work tasks cause silica exposure and how to limit exposure.

Construction

Over 2 million construction workers are exposed to silica in over 600,000 U.S. workplaces. OSHA’s silica standards for construction establish that employers must:

• create a written exposure control plan that includes protection methods and procedures to restrict access to high-exposure worksite areas.
• designate a competent person to implement the plan.
• keep records of exposure data and measurements, as well as medical exams.
• train workers on which work tasks cause silica exposure and how to limit exposure.
• offer medical exams every three years for workers exposed at or above the action level for 30 days or more per year.
• limit housekeeping methods that expose workers to silica dust.

OSHA’s Construction standards allow for some workplace flexibility in the approach to silica dust protection, which is found in Table 1 of the standard. This lists 18 common construction tasks and the most effective dust control methods for each; employers who can practice these methods aren’t required to measure employee exposure to silica and are not subject to the PEL. If these measures cannot be enacted, employers can decide independently which dust controls are most effective for their worksite but are required to monitor silica dust levels.

The impact of silica dust may occur after a short period of time, or it may take years to cause obvious harm to the lungs. Dust scarring cannot be reversed, so the most effective way to protect employees is to evaluate their tasks and working environment for silica exposure hazards. Preventing employees from breathing silica is crucial to ensuring their long-term health and safety.