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Crystalline Silica: Sampling/Testing of Workers for Respirable Silica

If you need crystalline silica sampling/testing of workers discussed in this article call us at 1-800-344-4414 or email us at info@atlenv.com for details and a free estimate.


Written By: Robert E. Sheriff, MS, CIH, CSP, President

November 6, 2018


Crystalline silica has been classified as a lung carcinogen. OSHA issued its final rules for controlling worker exposure to crystalline silica on March 23, 2016. The specific OSHA regulation is 29CFR1926.1153 (Construction Standard) and 29CFR1910.1053 (General Industry/Marine). Sampling of workers that handle sand (silica) such as concrete mixing, paving, gravestones, countertops, marble products, sandblasting, oil & gas fracking, crushed stone products all require air sampling of workers to define exposure and the need for engineering controls or respiratory protection.

Although silica is one of the more common elements on earth, it’s the crystalline form of silica that can cause serious damage to the lungs—and even be fatal. The lung condition is called silicosis. The crystalline silica scars the lungs and such scarring becomes progressive—conceivably leading to further lung damage, tuberculosis, and lung cancer. OSHA has set the Permissible Exposure Limit (PEL) at 50 micrograms per cubic meter (50 ug/m3) and the action level at 25 ug/m3.

Formerly the PEL was based on a formula where the increase in percent of silica decreased the allowable PEL. This could be quite confusing to interpret.

Sampling for the forms of silica that cause disease (alpha quartz, crystobilite, and tridymite) involves the use of a respirable dust cyclone and a filter to capture the airborne particulates. The current use of a respirable dust cyclone that samples at 1.7 liters per minute (LPM) is not sensitive enough to reach the OSHA action level when sampling for an 8-hour time-weighted average. For an accurate sample, a respirable dust cyclone that samples at 2.4 LPM or greater is recommended for full shift sampling.

Also note that there are alternate methods of sampling but they should be performed by a properly equipped and knowledgeable Industrial Hygienist.

Also ensure that the laboratory analyzing the samples is accredited by the American Industrial Hygiene Association (AIHA) and they use the accepted method for analysis of silica samples (generally OSHA Method I.D. 142 or NIOSH 7500).

The general provisions to both Construction and General Industry are generally the same:


  • Permissible Exposure Limit (PEL) over an 8-hour shift is 50 mg/M3 of air.
  • Action level of 25 ug/M3 of air.
  • Requires employers to use engineering controls to limit worker exposure where sampling indicates a level above the PEL. Respirators as a supplement to engineering controls where such efforts won’t adequately control exposure.
  • Develop a written exposure control plan.
  • Medical exams if exposed at or above action level for 30 days or more per year starting June 23, 2018.
  • Training.
  • Final Rule took effect on June 23, 2016, (60 days after publication).


Compliance dates for the separate regulations are different:

For Construction, the effective date is June 23, 2017.

For General Industry and Maritime, the effective date is June 23, 2018. (Note the 1 year extension over Construction).

NOTE: Hydraulic Fracking, although part of Construction, has an effective date of June 23, 2018 but engineering controls have a compliance date of June 23, 2021 (5 years!).

Those of us in the occupational health profession have expected these new regulations for some time. There are many activities in Construction and Industry where exposures have not been well controlled. Also, the previous regulation had a formula for calculating the exposure level (the greater the % silica the lower the PEL) which was confusing and difficult to explain.

The new standards have a lower PEL and more protection of workers but also easier to comprehend and explain to involved employers and employees.

From experience, the most likely sources of overexposure in Construction are:


  • Dry concrete cutting
  • Sand and gravel operations
  • Concrete mixing—including Redimix
  • Mining including rock, salt, coal, other minerals
  • Construction excavation especially where rock is involved
  • Dry aspects of fracking—all stages
  • Some wet concrete cutting operators


Overexposure potential in General Industry are:


  • Sand and concrete/mortar packaging
  • Stone cutting
  • Marble cutting
  • Brick and block manufacturing
  • Gravestone cutting and lettering
  • Countertop manufacturing
  • Refractory products (bricks and cement)
  • Glass manufacturing
  • Foundries especially sand casting


The final rule can be found on OSHA’s website at www.osha.gov/dsg/topics/silicacrystalline/

Atlantic Environmental has the capability of monitoring worker exposure, developing control plans and performing the necessary training, as well as recommending solutions to identified problems.


Our primary service areas for Industrial Hygiene Sampling are: NJ, NY, NYC, PA, CT, DE, (Boston) MA, RI, Wash DC, WI, MD, MI, (Chicago) IL, VA, IN, (Atlanta) GA, AL, NC, SC, TN, (Dallas, Ft Worth) TX, OK, DC, AR, we can service most other areas of the U.S. but with some added travel charges.

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