Sampling for Silica
The action limit (AL) for silica is now at 25 ug/M3 and the permissible exposure limit (PEL) for silica is now 50 ug/M3. If employers are above the AL and below the PEL, there are several mandatory requirements, which are listed below. Employers must control silica exposures to below the PEL using engineering controls and supplement with respirators where necessary.
However, the updated standard emphasizes the use of engineering controls over air sampling and respirators to control exposures. If a contractor chooses to follow the requirements listed in Table 1 fully and completely, OSHA assumes they are in compliance and does not require sampling.
If employers choose not to follow Table 1, the Performance Option or Scheduled Sampling options must be implemented Under these options, employers must either use objective data - sampling data based on prior exposures or other calculations - or perform periodic air sampling. Note that for objective data to be valid, it must have been collected under similar conditions (e.g., environmental conditions) to the current task.
The table below explains when sampling is needed to maintain compliance and make sure workers are not exposed above the OSHA PEL. Click here to download this chart as a PDF.