Crystalline silica is one of the basic components of soil, sand, granite, and many other minerals. Quartz is the most common form of crystalline silica. Cristobalite and tridymite are two other forms of crystalline silica. Respirable particles may be released when workers chip, cut, drill, blast, or grind materials that contain crystalline silica.

Occupational exposure to respirable crystalline silica occurs from cutting, sawing, drilling, and crushing of concrete, brick, ceramic tiles, rock, and stone. Industrial operations that process or use large quantities of sand, such as foundries, glass production, that manufacture of pottery and concrete products, etc. can be associated with significant exposure. OSHA estimates that more than 2.3 million workers in the United States are potentially exposed to dust containing crystalline silica with nearly 90% of those workers employed in the construction industry. {

The finest particles of crystalline silica dust in the workplace represent the greatest concern. This is the respirable fraction of the dust, which corresponds to the proportion of the airborne dust penetrating deep into lungs, where the particles can stay for a long time and cause lung damage.

Questions to ask when deciding on a laboratory

  • How long has the laboratory analyzed crystalline silica?
  • Is the laboratory knowledgeable about the type of workplace you are sampling and the substances present?
  • Is the laboratory aware of the analytical method limitations?
  • Do laboratory staff know about the sampling method limitations?

Quality Assurance and Quality Control

  • Does the laboratory have a quality control program?
  • Is the laboratory accredited for silica analysis?
  • Does the laboratory participate in blind proficiency testing (e.g., AIHA PAT) for silica? and Is the laboratory rated proficient in silica analysis?
  • Does the laboratory examine outliers?
  • Does the laboratory provide pre-weighed media?

Accredited Laboratory for Crystalline Silica Analysis
Occupational Safety and Health Administration (OSHA) has established on their website recommendations for sample collection and laboratory requirements needed for silica determination. The choice of laboratory is determined by the quality assurance/ quality control, experience and participation in proficiency programs designed for silica analysis. (

OSHTECH has been analyzing silica for the last 20 years. Our laboratory (ID 1587811) is accredited by the AIHA Laboratory Accreditation Programs, LLC in the Industrial Hygiene accreditation program for Silica Fields of Testing as documented by the Scope of Accreditation Certificate and Associated Scope. Our laboratory participates in international rounds of quality control testing four times a year. OSHTECH has been rated as proficient all these years. Our laboratory analyzes thousands of samples per year from clients all over the world.

The QA/QC program is based on AIHA specification and consists of a series of testing during the analysis. In the simplest case, one silica sample requires five to ten quality control samples that are employed as internal control for the experiment and recorded and statically controlled to achieve the quality controls required by OSHA requirements.

Our staff is highly qualified have in depth knowledge of the methods used for analysis. We are continually supporting our clients by replying to questions and comments related to the methods.

Our laboratory is also accredited for gravimetric analysis of total, respirable and inhalable particulates. The laboratory is able to combine particulate analysis with silica collected on the same sampling media. OSHTECH offers un-weighed media and pre-weighed media for analysis of crystalline silica or crystalline silica combined with particulates.

Consulting Services for Silica
OSHTECH also offers consulting services for silica including workplace exposure monitoring, risk assessments, and personal air sampling to quantify dust and silica in the air.