Silicosis Resources for Employers and Contractors

If It’s Silica… It’s Not Just Dust!

Occupational Exposure Limits
Occupational exposure limits are intended to set the airborne concentrations of substances to which workers can be exposed, on a daily basis, without significant risk of adverse health effects. The OSHA PEL (which is essentially 0.1 mg/m3) is the regulatory enforceable exposure limit. However, the OSHA PEL is considered to be less protective than other occupational exposure limits for silica, such as the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) of 0.025 mg/m3, and the National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL) of 0.05 mg/m3, which are based on more current toxicological data.

Construction/Manufacturing Sectors

What is Silicosis?

Silicosis Fact Sheets

Silica Dust Levels


Respirators should not be the primary method of protection. If engineering controls cannot keep dust levels below the NIOSH REL (0.05 mg/m3), then respirators should be used. Always use NIOSH-approved respirators.

Note: When respirators are used, the employer must establish a comprehensive respiratory protection program as required by the OSHA Respiratory Protection Standard. See also OSHA Respiratory Protection e-Tool.

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Last Reviewed: 10/11/2016