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Silica Dust: Understanding the Safe Harbor Provision for Construction

September 27, 2016

As you’re probably aware if you’re in the construction industry, the new permissible exposure level (PEL) for silica dust is a mere 20% of the previous one.

In addition to this much stricter requirement, OSHA’s silica dust rule also requires employers to implement many new practices. These include engineering controls and housekeeping, as well as sampling and analyzing the air workers breathe and monitoring workers’ health.

Recognizing that such an aggressive program might be difficult for many construction companies to implement, OSHA has provided an alternative way for organizations to become compliant, a “safe harbor” provision. Essentially, as long as employers fully and properly implement OSHA’s specified control measures for construction tasks, they will be considered in compliance with the rule.

This article provides a quick Q&A to help you better understand this provision and its requirements.

Where can I find the specified exposure control methods for each task?

The tasks and their controls are listed in Table 1 of CFR: 1926.1153, which is the silica dust standard for the construction industry.

I’m not in construction. Does Table 1 still apply?

No. There is a separate standard for general industry and maritime, which you can find here.

What tasks are covered by Table 1?

OSHA has identified 18 pieces of equipment/tasks that commonly produce silica dust, such as sawing, drilling, milling, and crushing. For each task, Table 1 specifies the required engineering and work practice control methods and whether or not respiratory protection is required.

As examples, here are three of the tasks and their requirements:

Equipment/task Engineering and work practice control methods Required respiratory protection and minimum assigned protection factor (APF)
<4 hours/shift >4 hours/shift
Stationary masonry saws Use saw equipped with integrated water delivery system that continuously feeds water to the blade

Operate and maintain tool in accordance with manufacturer’s instructions to minimize dust emissions

None None
Dowel drilling rigs for concrete For tasks performed outdoors only:

Use shroud around drill bit with a dust collection system. Dust collector must have a filter with 99% or greater efficiency and a filter-cleaning mechanism

Use a HEPA-filtered vacuum when cleaning holes

APF 10 APF 10
Handheld grinders for mortar removal (i.e., tuckpointing) Use grinder equipped with commercially available shroud and dust collection system

Operate and maintain tool in accordance with manufacturer’s instructions to minimize dust emissions

Dust collector must provide 25 cubic feet per minute (cfm) or greater of airflow per inch of wheel diameter and have a filter with 99% or greater efficiency and a cyclonic pre-separator or filter-cleaning mechanism

APF 10 APF 25

View the standard for the full table.

What about tasks not covered in Table 1?

Table 1 covers many common construction tasks. But it doesn’t account for everything that happens at a construction site.

For tasks not covered in Table 1, employers must implement engineering and work practice controls and provide respiratory protection to ensure silica dust exposure is below the PEL.

There are two options for assessing exposure:

  • Performance option. This option requires employers to assess each employee’s silica dust exposure over the course of 8 hours based on “any combination of air monitoring data or objective data sufficient to accurately characterize employee exposures to respirable crystalline silica.”
  • Scheduled monitoring option. This option requires employers to sample each employee’s breathing zone air “on each shift, for each job classification, in each work area.” If several employees perform the same job in the same place, a representative sample is acceptable.
  • If exposure is below the PEL, the monitoring must be repeated within 6 months.
  • If exposure is above the PEL, the monitoring must be repeated within 3 months.

Exposure must also be reassessed if there’s a change in the process or any reason to think the silica dust level has increased.

What else do I have to do to be compliant?

Regardless of whether you choose the specified exposure control methods of Table 1 or alternative exposure control methods, there are still some additional steps to achieve full compliance.

  • Housekeeping. Wet sweeping and HEPA-filtered vacuuming are recommended. Dry sweeping, dry brushing, and compressed air are only allowed if the recommended options aren’t feasible.
  • Written exposure control plan. The plan must identify the tasks that put workers at risk. It must also describe all engineering controls, housekeeping measures, and procedures to restrict access to work areas used to limit exposure to silica dust.
  • Medical surveillance. Employers must provide free medical surveillance for employees who meet certain requirements.
  • Hazard communication. Employers must inform employees about their exposure and provide training to help them reduce their personal risks.
  • Recordkeeping. Records must be kept for all air monitoring data, objective data, and medical surveillance data.

Have more questions? Ask a Nilfisk expert.

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