Silica Regulatory Alert

  • 2016-03-29

OSHA’s Revised Silica Standard

It is estimated that 2.3 million workers are exposed to respirable crystalline silica in the workplace, including 2 million construction workers who drill, cut, crush, or grind silica-containing materials such as concrete and stone. In an effort to curb lung cancer, silicosis, chronic obstructive pulmonary disease, and kidney disease in America’s workers, the Occupational Safety and Health Administration (OSHA) has revised the rule for exposure limits to respirable crystalline silica.


Original standards were set by the Department to limit worker exposure in 1971. Back then, the construction standard for silica used light microscopy and low magnification as a measurement technology. As this methodology became obsolete, OSHA began enforcing the general industry standard which was a respirable dust level determined by 10mg/m3/% silica+2. For example, if the % of silica in dust was analyzed at 3%, then the Permissible Exposure Level (PEL) was 2 mg/m3 (10/3+2) (2000 ug). Note that the exposure was actually determined by the concentration of respirable dust.

It was recognized that these standards no longer adequately protected workers from silica-related diseases. In addition, workers are being exposed to silica in new industries, such as stone or artificial stone countertop fabrication.  As a result, OSHA has established a new standard, instituting a PEL of 50 ug/m3, which identifies the actual silica exposure determined from the % identified in the dust.

Key Provisions in the New Standard

  • Reduces the PEL for respirable crystalline silica to 50 micrograms per cubic meter of air (a definite fixed standard for construction, which takes them out of the current “grey zone” created by using the old general industry standard)
  • Use of engineering controls, such as water or ventilation, to limit worker exposure to the PEL
  • Provides respirators when engineering controls cannot adequately limit exposure
  • Limits worker access to high exposure areas and develops a written exposure control plan
  • Provides medical exams to highly exposed workers, and trains workers on silica risks and hot wo limit exposures

Workers most likely exposed in construction are masons (mixing bags, chipping concrete, etc., and demolition of concrete).  It should also be noted that WCD has observed exceedance for general laborers doing dry sweeping of construction dust in cleanup/housekeeping.

OSHA estimates that this new rule will save over 600 lives and prevent more than 900 new cases of silicosis each year. The Final Rule is projected to provide net benefits of about $7.7 billion annually. The standards contained in the final rule take effect on June 23, 2016. Industry compliance for the construction-related standards of this rule must be implemented by June 23, 2017.

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