New Rule:

Effective June 2016, the Occupational Safety and Health Administration (OSHA) finalized the Crystalline Silica Rule for General Industry, Maritime and Construction. The final rule establishes new exposure limits and action levels, as well as specifies requirements for worker exposure assessments, exposure controls, medical surveillance, respiratory protection, hazard communication, and recordkeeping. Any in

dustry that utilizes any form of sand, concrete, stone or mortar during work or manufacturing activities could have workers that are exposed to respirable crystalline silica. This blog provides an overview addressing key points regarding silica and its health effects, and highlights the drivers for the new rule.


Silica is a compound composed of the elements silicon and oxygen (SiO2) that is found both in the natural environment and in manufacturing processes. In its crystalline state, silica is a common mineral found in many naturally occurring materials used in industrial products as well as at construction sites. Materials like sand, concrete, stone and mortar contain crystalline silica in one of three mineralogical forms including quartz, cristobalite, and/or tridymite or any combination of the three. Quartz is the most common form of crystalline silica (i.e., sand).

The health concern of this mineral comes from the inhalation of very small (“respirable”) crystalline silica dust particles. Inhalation of this dust can penetrate deep into the lungs and may expose workers to multiple diseases, including silicosis, an incurable lung disease that can lead to disability and death. Respirable crystalline silica can also put workers at risk for developing lung cancer, chronic obstructive pulmonary disease, and kidney disease.


OSHA has identified multiple industries that have the potential for silica dust exposure. Within these industries, OSHA estimates approximately 2.3 million workers throughout the United States have potential exposure to respirable crystalline silica with over two million in the construction industry and over 300,000 in general industry operations and maritime operations. Some of these industries include:

  • Electronics
  • Foundries
  • Ceramics, clay, pottery, stone, and glass
  • Construction
  • Agriculture
  • Maritime
  • Road construction
  • Use of concrete products
  • Railroad industry
  • Slate and flint quarrying and crushing
  • Use and manufacture of abrasives
  • Abrasive blasting
  • General production
  • Mining
  • Countertop manufacturing
  • Roofing
  • Dental laboratories

Below is a further breakdown of activities with some common workplace operations and equipment involving potential exposures to respirable silica while performing specific tasks:

  • Cutting, sawing, drilling, and crushing of concrete, brick, rock, and stone products;
  • Operations using sand products (concrete construction, road building, glass manufacturing, foundries, sand blasting, drywall finishing and hydraulic fracturing);
  • Manufacturing or production of filler in plastics, artificial stones, rubber, and paint, and as an abrasive in soaps and scouring cleansers;
  • Mining and earth drilling (and operations involving the disturbance of the earth’s crust);
  • Use of equipment including, but not limited to, stationary masonry saws, handheld masonry saws, hand- operated grinders, tuckpointing/mortar removal, jackhammers, rotary hammers and similar tools, and vehicle-mounted rock drilling rigs.

ATC’s industrial hygiene professionals can assist you with understanding and complying with this rule. Contact us for additional information.

About the Author:

Catherine G. McLain, MS, CIH is a Certified Industrial Hygienist with ATC and has over 20 years of diverse experience in the field of building science and industrial hygiene. Her extensive experience in the discipline include: consulting aspects associated with asbestos, microbial, and lead; indoor air quality; area and personnel monitoring for chemical, physical, and biological hazards; evaluation of tasks and workplace exposures; as well as general environmental health and safety.