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What is the permissible exposure limit (PEL) for silica?

By Safeopedia Staff | Last updated: September 20, 2018
Presented by AD Safety Network

Crystalline silica is common on construction sites and used in several industrial products including glass, ceramics, and concrete. Despite being a useful substance, exposure to silica can cause serious lung and kidney diseases that can be disabling and even fatal. With more than 2.3 million workers potentially exposed to dust containing silica, it’s an important issue across several industries (learn more about Indoor Air Quality: The Invisible Hazard in Every Workplace).

OSHA has recently updated the permissible exposure limit (PEL) for its respirable crystalline silica standard (29 CFR 1926.1153). Supported by NIOSH and the American Public Health Association, OSHA has cut the former limits in half in an effort to lower the number of employees affected by silica-induced illnesses. Averaged over an eight-hour work day, employee exposure should not surpass 50 micrograms of crystalline silica per cubic meter of air (find out more in The Who, What, and Why Behind the New Silica Standard).

Current air sampling methods are acceptable for gauging the levels of silica at a specific site. Remember, in this case larger samples mean more precise results for the team.


To keep silica levels low, teams are advised to wet down work sites, enclose or isolate parts of a workspace, or use vacuum or ventilation systems to filter silica-containing dust from the air. In the event that these techniques are insufficient to maintain exposures at or below the suggested PEL, respirators can be used but should not be the first choice or go-to option in most situations. Getting familiar with the new silica standard and PEL will help you protect your workers from unnecessary dangerous exposure.

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