Guide to the OSHA silica standard
25 January 2020


Crystalline silica is fine enough to be inhaled, and it’s usually found in common construction materials like mortar, brick, and stone. These particles form whenever construction workers crush or grind these materials. And due to its small size, silica travels deep into the lungs and causes conditions like silicosis, kidney problems, and obstructive pulmonary disease. To make matters worse, symptoms begin to surface years after the exposure occurs.

OSHA’s statistics show that around 2.3 million Americans face silica exposure. Hence, to improve worker safety in work environments that require the use of silica, the OSHA publishes a set of guidelines for exposure, termed the Silica Standard.

Updated PEL

The previous PEL (permissible exposure limit) was outdated, and the new one calls for a maximum limit of 50 µg/m3 during an 8-hour period in highly affected industries. It’s critical that employees’ exposure shouldn’t exceed the limit at any point.

Updated Action level

The revised standard sets an action level of 25 µg/m3, so employers need to prove that workers won’t be exposed to this level of crystalline silica or higher.


In the situation that a workplace’s silica exposure rises higher than the action level, employers need to meet compliance requirements. This includes housekeeping arrangements, hazard communication, medical surveillance, and respiratory protection.

Implications of Prolonged Silica Exposure

Upon inhalation, respirable crystalline silica can damage the delicate tissues inside your lungs, which negatively impacts your breathing pattern, circulatory system and its ability to transport oxygen and nutrients.


Among the other conditions that develop as a result of silica exposure, silicosis is the most common. It can develop at any point after a few weeks of severe exposure, or even a decade later after exposure. Silicosis refers to fibrosis in the lungs, and it’s termed as an occupational disease because of how it mainly occurs due to an occupational hazard.

The Importance of Objective Data Methodology

In the recently revised silica standard, the OSHA highlighted that employers need to monitor their workplace’s air quality to find out whether it complies with their set limits. It also calls for the need to conduct personal assessments for silica exposure in different areas. Specifically, OSHA used the term ‘objective data’, which can be derived through a monitoring test, or any combination of data that an employer sees fit (if they opt out of the monitoring option). 

Types of data and exposure assessment strategies using direct reading instruments that may qualify as objective data include: 

• Exposure mapping (determining exposures associated with particular locations based on information obtained from sources that may include personal samples, area samples, and direct- reading instruments); 

• Calculations based on the composition of a substance;

•Calculations based on the chemical and physical properties of a substance (in those instances where a substance’s physical and chemical properties demonstrate employee exposure to silica associated with a particular product or material or a specific process, task, or activity); 

How can employees use objective data with streamlined monitoring 

When assessing the issue of silica exposure objectively, employers can quickly assess exposures in real time and reduce the need for cumbersome sampling protocols. By using a connected exposure monitor, the time to testing and improvement can be cut down from months to day.

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