Crystalline Silica
Job Activities Posing Risk
A construction worker in dust while operating a dowel drill on a concrete runway. Photo by NIOSH.
There are various industries where workers can have jobs at risk for exposure to crystalline silica dust. Examples include:
- Construction
- Mining
- Oil and gas extraction
- Stone countertop
- Foundries and other manufacturing settings
- Dentistry
Job activities, such as cutting, quarrying, drilling, and abrasive blasting, can put a worker at risk for exposure if proper engineering controls and respiratory protection are not implemented.
Sources of Exposure
Crystalline silica is found in:
- Soil
- Sand
- Concrete
- Mortar
- Granite and other minerals
- Artificial stone
The most common form of crystalline silica is quartz. However, it can also occur in the form of cristobalite and tridymite. Exposure to cristobalite typically occurs in foundries where intense heat of molten metal causes cristobalite to form in clay molds. Hazardous levels of respirable dust can be released into the air when working with materials that contain crystalline silica.
- Manufacturing of glass, pottery, ceramics, bricks, concrete, and artificial stone
- Abrasive blasting
- Foundry work
- Hydraulic fracturing
- Stonecutting
- Rock drilling
- Quarry work
- Tunneling
Resources for Silica in Industry
Health Hazard Evaluations
The Health Hazard Evaluation (HHE) Program provides assistance to employers and employees in evaluation of new and recurring workplace hazards and in implementing preventive measures. Search the HHE database to find respirable crystalline silica evaluations that have been conducted in a number of different industries.
NIOSH Construction Safety and Health Topic Page
Resources related to safety and health for construction workers.
OSHA Fact Sheet – OSHA’s Respirable Crystalline Silica Standard for Construction
DSG FS-3681 (Dec 2017)
The Occupational Safety and Health Administration’s (OSHA) standard requiring employers to take steps to protect workers from exposure to respirable crystalline silica.
Electronic Library of Construction Occupational Safety and Health (eLCOSH): Silica
Collection of resources regarding information on silica. Some documents include versions in additional languages.
Workplace Solutions: Reducing Hazardous Dust Exposure When Rock Drilling During Construction
NIOSH Publication No. 2009-124 (April 2009)
Construction workers may be exposed to hazardous dust containing crystalline silica during site preparation when drilling systems are used. The National Institute for Occupational Safety and Health (NIOSH) found that drill dust could be decreased by using wet or dry dust reduction engineering controls, enclosed cabs, and implementing a dust control program.
En Español
Workplace Solutions: Reducing Hazardous Dust in Enclosed Operator Cabs During Construction
NIOSH Publication No. 2009-123 (April 2009)
Construction workers may be exposed to hazardous dust containing silica when working in enclosed cabs during construction activities. The National Institute for Occupational Safety and Health (NIOSH) found that equipment operator exposure could be reduced by retrofitting air pressurization and filtration systems on existing cabs, using sweeping compounds on soiled floors, and implementing a dust control program.
En Español
Workplace Solutions: Control of Hazardous Dust When Grinding Concrete
NIOSH Publication No. 2009-115 (April 2009)
Construction workers are exposed to hazardous dust when using handheld electric grinders to smooth poured concrete surfaces after forms are stripped. The National Institute for Occupational Safety and Health (NIOSH) found that exposures could be reduced if a local exhaust ventilation (LEV) shroud was attached to the grinder.
En Español
Workplace Solutions: Control of Hazardous Dust During Tuckpointing
NIOSH Publication No. 2008-126 (September 2008)
Construction workers are exposed to hazardous dust when grinding or cutting mortar or cement from between the bricks of old buildings. The National Institute for Occupational Safety and Health (NIOSH) found that exposures could be reduced using tool-mounted local exhaust ventilation and work practices.
En Español
Workplace Solutions: Water Spray Control of Hazardous Dust When Breaking Concrete with a Jackhammer
NIOSH Publication No. 2008-127 (May 2008)
Construction workers are exposed to hazardous dust when using jackhammers to break concrete pavement. NIOSH found that exposures could be reduced by using a water-spray attachment. A study to measure exposures found that jackhammer operators who break concrete were exposed to about 6 times the NIOSH recommended exposure limit (REL).
En Español
Silicosis – Working with Cement Roofing Tiles: A Silica Hazard
NIOSH Publication No. 2006-110 (2006)
Although respirable silica is a recognized health hazard in the construction industry, only recently has this exposure been documented in roofers. NIOSH has measured respirable silica levels up to four times the recommended exposure limit around roofers cutting cement products such as when roofing tiles are cut during the installation process.
En Español
Silicosis: Learn the Facts!
NIOSH Publication No. 2004-108 (August 2004)
This document presents information in an easy to read format describing silica exposures, the effects of silicosis, and methods to protect against silicosis.
En Español
Hazard Control 27: New Shroud Design Controls Silica Dust From Surface Mine and Construction Blast Hole Drills
DHHS (NIOSH) Publication No. 98-150 (1998)
On surface coal mining and construction sites, blast hole drills are notorious sources of airborne respirable dust that may contain significant amounts of silica. This Hazard Control offers information on a unique circular deck shroud which may reduce dust up to 99%.
En Español
Hazard Control 30: Control of Drywall Sanding Dust Exposures
NIOSH Publication No. 99-113 (1999)
Construction workers who sand drywall joint compound are often exposed to high concentrations of dusts and, in some cases, respirable silica. This publication focuses on two methods of drywall sanding — vacuum sanding systems and pole-sanding, which assist in reducing exposure.
En Español
Construction Workers: It’s Not Just Dust!…Prevent Silicosis
NIOSH Publication No. 97-101 (1997)
This pamphlet contains brief information about what silicosis is, its symptoms, how construction workers get exposed, activities in which silica dust may be present, and silicosis prevention.
Silica…It’s Not Just Dust: What Rock Drillers Can Do to Protect Their Lungs from Silica Dust
NIOSH Publication No. 97-118 (July 1998)
This bulletin, produced by an interagency team from NIOSH, MSHA and OSHA describes how to minimize the risks of silicosis for rock drillers.
Preventing Silicosis and Deaths in Construction Workers
NIOSH Publication No. 96-112 (1996)
This Alert describes six case reports of construction workers who have died or are suffering from silicosis. In addition, the Alert cites examples of five construction operations that used poor dust controls and two operations that used good dust controls.
En Español
NIOSH Dentistry Directory Page
Resources related to safety and health for dentist workers.
Silicosis in Dental Laboratory Technicians—Five States, 1994–2000
Centers for Disease Control and Prevention (CDC) Morbidity and Mortality Weekly Report (MMWR): 53(09);195-197 (Mar 2004).
During 1994 – 2000, occupational disease surveillance programs in five states identified nine confirmed cases of silicosis among persons who worked in dental laboratories. This report describes three of the cases and underscores the need for employers of dental laboratory technicians to ensure appropriate control of worker exposure to crystalline silica.
Silicosis and Silica Exposure in Dental Technicians
New Jersey Department of Health and Senior Services (NJDHSS), Public Health Services Branch, Division of Epidemiology, Environmental and Occupational Health, Occupational Health Service, Occupational Health Surveillance Program (slide presentation 2008).
What Dental Technicians Need to Know About Silicosis
New Jersey Department of Health and Senior Services (NJDHSS), Public Health Services Branch, Division of Epidemiology, Environmental and Occupational Health, Occupational Health Service, Occupational Health Surveillance Program (Brochure)
Respirable Dusts: Mining Topic Page
NIOSH topic page on respirable dust in mining.
Electronic Code of Federal Regulations – Mandatory Health Standards, Underground Coal Mines
Title 30, Part 70 (Jan 2020)
Respirable crystalline silica can be found in three forms – quartz, cristobalite, and tridymite. To control quartz exposure of mine workers, the Mine Safety and Health Administration (MSHA) established permissible exposures limits (PELs) and conducts personal dust sampling to assess compliance with these PELs.
Dust Control Handbook for Industrial Minerals Mining and Processing, Second Edition
NIOSH Publication No. 2019-124 (Mar 2019)
A successful collaborative effort by government and industry toward protecting the health of U.S. workers.
NIOSH Testing a Revised Inlet for the Personal Dust Monitor
Journal of Occupational and Environmental Hygiene 2019 Mar; 16(3): 242-249.
NIOSH research on the development of a continuous personal dust monitor (CPDM) designed for use in underground coal mines.
MSHA Handbook Series for Coal Mine Health Inspection Procedures – Chapter 1
Handbook Number: PH89-V-1, 27 (June 2016)
Procedures and guidelines for conducting respirable coal mine sampling inspections, evaluating sampling results, establishing and removing sampling entities, establishing reduced dust standards due to quartz, and monitoring the operators’ respirable dust control and sampling programs.
Best Practices for Dust Control in Coal Mining
NIOSH Publication No. 2010-110 (Jan 2010)
This publication identifies available engineering controls that can help the industry reduce worker exposure to respirable coal and silica dust.
Mining Product: Best Practices for Dust Control in Metal/Nonmetal Mining
NIOSH Publication No. 2010-132 (May 2010)
This publication identifies available engineering controls that can help underground and surface metal/nonmetal mining operations in reducing worker exposure to silica dust.
MSHA Handbook Series for Coal Mine Health Inspection Procedures – Chapter 5
Mineral Dusts – Gravimetric Method (Oct 2006)
Exposure to mineral dust is determined by the gravimetric method (using a sampling pump and a pre-weighted filter cassette to determine dust concentrations in the mine atmosphere.
Evaluation of an Improved Prototype Mini-Baghouse to Control the Release of Respirable Crystalline Silica from Sand Movers
J Occup Environ Hyg (Jan 2018)
NIOSH research identified at least seven sources where respirable crystalline silica aerosols were generated at hydraulic fracturing sites. NIOSH researchers developed an engineering control to address one of the largest sources of silica aerosol generation escaping from thief hatches on the top of sand movers.
The Development and Testing of a Prototype Mini-Baghouse to Control the Release of Respirable Crystalline Silica from Sand Movers
J Occup Environ Hyg (Aug 2016)
This manuscript details the results of a trial of the NIOSH mini-baghouse at a sand mine in Arkansas in 2013.
In-Depth Survey Report: Field Evaluation of the NIOSH Mini-Baghouse Assembly or Control of Silica Dust on Sand Movers
NIOSH In-Depth Survey Report (Jul 2016)
This report details the results of a trial of the 3rd generation of the NIOSH-developed mini-baghouse retrofit assembly that occurred at Southwestern Energy Sand Company in North Little Rock, Arkansas in 2015. This trial is a follow-up to the 2013 test of the 2nd generation of the technology.
NIOSH-Designed Technology Can Reduce Workers’ Exposure to Silica at Hydraulic Fracturing Sites
NIOSH Update (Nov 2015)
Researchers have developed and tested a prototype called the “mini-baghouse” that can protect oil and gas extraction workers by effectively controlling silica dust at hydraulic fracturing worksites.
NIOSH Oil and Gas Extraction Program
NIOSH Oil and Gas Extraction Program resources for publications, topic pages, related NIOSH Centers, and science blogs.
Occupational Exposures to Respirable Crystalline Silica during Hydraulic Fracturing
J Occup Environ Hyg (Jul 2013)
This report describes a previously uncharacterized occupational health hazard: work crew exposures to respirable crystalline silica during hydraulic fracturing.
OSHA/NIOSH Hazard Alert: Worker Exposure to Silica during Hydraulic Fracturing
OSHA/NIOSH Publication No. 2012-166 (Jun 2012)
A OSHA/NIOSH hazard alert identifies exposures to airborne silica as a health hazard to workers conducting some hydraulic fracturing operations during recent field studies.
NIOSH Science Blog: Outbreak of Silicosis among Engineered Stone Countertop Workers in Four States
(Oct 2019)
This blog further discusses the MMWR report Severe Silicosis in Engineered Stone Fabrication Workers – California, Colorado, Texas, and Washington, 2017-2019.
Evaluation of Crystalline Silica Exposure during Fabrication of Natural and Engineered Stone Countertops
NIOSH Health Hazard Evaluation Report No. 2014-0215-3250 (Mar 2016)
The Texas Department of State Health Services asked the Health Hazard Evaluation Program requested assistance to evaluate silica exposure in a manufacturing plant. The plant makes natural and engineered stone countertops.
Centers for Disease Control and Prevention (CDC) Morbidity and Mortality Weekly Report (MMWR):
Severe Silicosis in Engineered Stone Fabrication Workers — California, Colorado, Texas, and Washington, 2017–2019
68(38);813–818 (Sep 2019)
Eighteen cases of silicosis, including two fatalities, are reported among stone fabrication workers in four states. Several patients also had autoimmune disease and latent tuberculosis infection.
Notes from the Field: Silicosis in a Countertop Fabricator – Texas, 2014
64(05);129-130 (Feb 2015)
A case of silicosis with progressive massive fibrosis was reported in a Hispanic male aged 37 years who worked for an engineered stone countertop company as a polisher, laminator, and fabricator. This is the first reported case of silicosis associated with exposure to quartz surfacing materials in North America.