The Big 4 of OSHA’s Silica Regulation

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This article builds on an article by Scott Thomas in 2017 that introduced OSHA’s new (at the time) Respirable crystalline silica regulation for construction; 29 CFR 1926.1153.

Silica is a naturally-occurring mineral found in building materials like sand, stone, concrete, bricks, blocks, glass, etc. If silica becomes airborne, some of the particles can be breathed in through the mouth and nose, which is why the “respirable” part is important.

Breathing silica dust particles can result in some solidly negative health effects. You might recall another naturally-occurring mineral that is also dangerous when breathed: asbestos. Silica dust exposure can lead to silicosis (incurable and potentially fatal), lung cancers, chronic obstructive pulmonary disease, and kidney disease. Taking those serious health conditions into account, it’s not surprising that OSHA issued the regulation to help protect workers.

The silica regulation sets two very low exposure levels that workers are allowed to breath. They are the 1.) action level (25 μg/m3) and 2.) permissible exposure level (50 μg/m3). Overall, if employees are exposed to silica dust above the action level, then protections for employees must be provided, and if the exposure is up to the permissible exposure limit, then even more protective measures must be put into place. Note: “μg” is the symbol for micrograms, a very small number. For the action level (25 μg/m3), it is the same as 0.000000025 g/m3.

Yes, the silica regulation is complicated even though OSHA tried to make it less so. To help with understanding, I’ve arranged it all into “Big 4” groups and kept the technical jargon to a minimum.

1. Big: Your Two Options

So, assuming your employees are exposed to silica dust, OSHA allows you two options for protecting them. Option 1 involves using Table 1, which lists a bunch of different work tasks and protective measures for each task and is pretty straight forward. Option 2 involves air monitoring your employees which is probably something you might want to hire out to a consultant or other specialist to help with. Both Options will be discussed below.

What is Table 1?

Option 1 (Table 1) is the easier option, but it’s important to note that Table 1 doesn’t have any wiggle room. If you don’t follow its requirements exactly, then you can’t use it. A section taken from Table 1 is found below as an example.

1.) Equipment/Work

Task OSHA gives a good list here of common job tasks that it considers to produce a lot of silica dust. These include work tasks like using masonry saws, drills, grinders, etc. in hand-held, walk-behind, and heavy equipment applications.

2.) Engineering/Work Practices

For each work task, there is a set of engineering/work practices required. The purpose there is to control/reduce the amount of silica dust that is produced. For example: if the work involves using a walk-behind concrete saw, then the saw must be equipped with an integrated water delivery system that continuously feeds water to the blade, and you must operate and maintain the saw in accordance with the manufacturer’s instructions for minimizing dust emissions.

3.) Required Respiratory Protection

This part of Table 1 is based on time/ duration: either less than 4 hours or 4 or more hours of doing the work task (such as using the walk-behind saw). OSHA then tells you what sort of respiratory protection the operator has to use. For the walk-behind saw, if it’s used properly, and outdoors, no respiratory protection is required. Respiratory protection that’s required is specified as having an Assigned Protection Factor (APF) of either 10 or 25; these are discussed in more detail below. Good news: some tasks don’t require a respirator at all.

What is Missing from Table 1?

So, what if the work task you’re doing isn’t listed in Table 1/Option 1? Well, then you have to go to Option 2. Sand blasting, for example, isn’t listed in Table 1. Here’s a tricky case: “Handheld power saws for cutting fiber-cement board (with blade diameter of 8 inches or less)” only specifies outdoor tasks. If you do that task indoors or in an enclosed area, you can’t use Table 1/Option 1. You need to review the information in Table 1 closely.

Air Monitoring/Option 2

Option 2 involves air monitoring, also called an exposure assessment. Option 2 is much more technical and involves special air monitoring equipment worn by workers, laboratory analysis, and other requirements that would make this article 2 or 3 times longer. So I’ve left all that out. I will say that some employers have the resources to handle Option 2, but others might just want to hire an experienced consultant.

2. Big: Equipment Use and Maintenance

Equipment use and maintenance is a major part of Option 1/Table 1. OSHA sets out exact methods of use for each type of work task, such use of integrated water delivery system, HEPA air filter, depth of cuts, etc. Note that other equipment issues (like keeping oil in the engine) might be important, but this is only about how the equipment controls silica dust. OSHA also requires that you follow the equipment manufacturer’s instructions, such as: maintaining ventilation airflow, filter changes, cutting blade rotation, etc., so plan on keeping those manuals handy.

Broadly speaking, two main areas OSHA focuses on are ensuring effective ventilation systems and using water to keep dust down. A possible third area is if you have heavy equipment with an enclosed cab, which involves requirements like keeping door seals tight, filtered air intake, heating/cooling, and others.

3. Big: Respiratory Protection

Respirators (sometimes called “dust masks”) may or may not be required.

Under Table 1/Option 1

  • Not required – Because you’re following Table 1…exactly.
  • Required – Because Table 1 says to provide respirators.

Under Air Monitoring/Option 2

  • Not required – If employee exposure is under the Permissible Exposure Limit (PEL).
  • Required – If employee exposure is over the Permissible Exposure Limit (PEL).

One of the important issues to be aware of is that when respirators are required, OSHA’s Respiratory Protection regulation, at 29 CFR 1910.134, then kicks in. Again, there’s not time in this article to get into those requirements, but it is something that requires more consideration. Some good guidance is found in OSHA’s booklet: Respiratory Protection Standard: Small Entity Compliance Guide (OSHA 3384).

What are Assigned Protection Factors (APFs)?

Table 1 may require that employees use respirators with APF 10 or APF 25. APF is a measure of how much protection the respirator provides. APF 10 provides less protection that APF 25.

A half-face respirator provides an APF 10. These are what most folks consider a “dust mask” (more technically is called a filtering face-piece respirator). These are made such that the entire respirator is disposable/thrown away after use. APF 10 is also provided by cartridge-style halfface respirators, where the face-piece is reusable, but the filter cartridge unscrews for disposal.

To achieve an APF 25, more complex types of respirators are required, such as a helmet/hood powered air-purifying respirator, or supplied-air style (airline) respirator. For very high levels of silica dust exposure, such as sand blasting, a respirator with APF 50 or higher might be needed.

4. Big: The Rest of the Iceberg

Again, this article would be too big if all the requirements of OSHA’s silica regulation were included. So, this last of the Big 4 is a catch-all, to point out there’s quite a bit more there. Regardless of whether you’re using Option 1/Table 1 or Option 2, the following are required:

  • Written silica exposure control program – This must include silica dust sources, control measures, etc. This program has to be reviewed at least annually.
  • Competent person – This person must be specifically designated. Skills required of the competent person are:
    1. Can identify existing and foreseeable respirable silica hazards;
    2. Is authorized to promptly eliminate or minimize silica hazards; and
    3. Has the knowledge and ability to implement the written exposure control plan.
  • Medical Testing – All employees who are required to wear a respirator for protection from silica dust for 30 or more days per year require medicals.
  • Housekeeping – OSHA requires specific methods to control spreading silica dust (like HEPA vacuums).
  • Training and Information – Must be provided to employees. Note: employees must demonstrate an understanding of important information like hazards of silica dust, control measures, etc.
  • Recordkeeping – If employees require medical testing or air monitoring is performed, then records must be kept.


If you made it through the Big 4, then you’ve done well to focus on some pretty technical regulatory requirements. Because of the serious health issues from silica dust, you need to pay attention and make sure that you’re protecting your employees as OSHA requires. The easiest path is to take Option 1/Table 1, but that requires a considerable amount of time and attention.

It might be best to get some help with dealing with silica dust. Certainly, you can hire a safety and health consultant, but you can also check with your local AGC office for guidance. Likewise, consider asking Kentucky OSHA (now called “KySafe”) for help; your tax dollars have already paid someone there to be an expert on respirable silica. You might as well get your money’s worth!

More information

KySafe Pages/default.aspx
OSHA Silica, Crystalline in Construction: silicacrystalline/construction.html
OSHA Small Entity Compliance Guide for Construction: https://www.osha. gov/Publications/OSHA3902.pdf
Respiratory Protection Standard: Small Entity Compliance Guide: Publications/3384small-entity-for-respiratory- protection-standard-rev.pdf

Author: Dr. David Stumbo, OHST, is a former KyOSHA compliance officer and is now an Assistant Professor with Eastern Kentucky University, Richmond, Kentucky. He offers safety consulting services via Stumbo Safety Solutions, LLC.