Safety and field operations

Silica exposure rules for contractors

OSHA's construction silica standard caps respirable crystalline silica at 50 micrograms per cubic meter over an 8-hour shift and lets most contractors comply by following the controls in Table 1, backed by a written plan, a competent person, and medical exams for heavy respirator users.

Two construction professionals review paper plans beside a tablet at a jobsite workbench.
Plan reviews connect field conditions, drawings, and the next decisions on a job. AI-generated illustration.

OSHA's silica rule for construction (29 CFR 1926.1153) applies whenever workers cut, grind, drill, chip, or crush concrete, block, brick, stone, or other materials that contain crystalline silica, unless exposure will stay below 25 micrograms per cubic meter over an 8-hour shift under any foreseeable condition. The permissible exposure limit is 50 micrograms per cubic meter as an 8-hour average. Most contractors comply by matching each task to Table 1 in the standard and using exactly the controls it lists. You also need a written exposure control plan, a competent person, housekeeping rules, training, and medical exams for anyone required to wear a respirator 30 or more days a year.

Who the silica rule covers

The standard covers all occupational exposure to respirable crystalline silica in construction work. Think of the trades that make dust from masonry and concrete: flatwork crews saw-cutting joints, electricians and plumbers coring and chasing, drywall and framing crews drilling anchors into slab, demo crews running jackhammers, and masons cutting block. If a task could foreseeably put a worker at or above 25 micrograms per cubic meter averaged over the shift, the rule applies to that work.

Two ways to comply: Table 1 or exposure assessment

The rule gives you a choice for each task.

  • Table 1 (specified exposure control methods): if the task is listed and you fully and properly use the listed engineering controls, work practices, and respirators, you do not have to measure exposure for that task.
  • Alternative exposure assessment: for tasks not on Table 1, or when you cannot follow its controls exactly, you must assess exposure with air monitoring or objective data, keep exposures at or below the limit, and repeat monitoring on the schedule the rule sets.

Under the scheduled monitoring option, results between the action level and the limit trigger repeat monitoring every 6 months, and results above the limit every 3 months. Workers must be told the results in writing within five working days, or the results must be posted. Small contractors almost always find Table 1 cheaper and simpler.

Four Table 1 entries from 29 CFR 1926.1153 (APF is the assigned protection factor of the required respirator)
Equipment or taskRequired controlsRespirator, 4 hours or less per shiftRespirator, more than 4 hours
Stationary masonry sawIntegrated water delivery to the blade, used per manufacturer's instructionsNoneNone
Handheld power saw, any blade sizeIntegrated water delivery to the blade, used per manufacturer's instructionsOutdoors none; indoors or enclosed APF 10APF 10 outdoors and indoors
Jackhammer or handheld powered chipping toolContinuous water stream or spray at the point of impact, or a shroud and dust collection systemOutdoors none; indoors or enclosed APF 10APF 10 outdoors and indoors
Handheld grinder for mortar removal (tuckpointing)Shroud and dust collection system meeting the airflow and filter specsAPF 10APF 25

What else the silica rule requires

Written exposure control plan

The plan must describe each task that involves exposure, the engineering controls, work practices, and respirators used for each task, the housekeeping measures, and the procedures used to restrict access to work areas when needed. Review it at least once a year and make it available on request. A job-specific page that lists the actual tasks on this project is far more useful than a generic company binder.

Competent person

The plan must name a competent person: someone capable of identifying existing and foreseeable silica hazards, and in practice someone with the authority to stop the work and fix them. That person makes frequent and regular inspections of job sites, materials, and equipment to make sure the plan is followed. On most small jobs this is the foreman.

Housekeeping

Dry sweeping and dry brushing are not allowed where they could add to exposure, unless wet sweeping, HEPA vacuuming, or other low-exposure methods are not feasible. Compressed air may not be used to clean clothing or surfaces where it could add to exposure, unless it is paired with a ventilation system that captures the dust or there is no feasible alternative.

Medical surveillance, training, and records

  • Medical exams: offered at no cost to workers required to wear a respirator 30 or more days a year. The first exam happens within 30 days of assignment (unless a qualifying exam was done in the last three years), then at least every three years.
  • Training: workers must be able to show they understand the health hazards, which tasks expose them, the controls and respirators in use, the contents of the standard, who the competent person is, and the purpose of medical surveillance.
  • Records: keep air monitoring results, objective data, and medical surveillance records under the access rules in 29 CFR 1910.1020.

Worked example: a concrete sub on a warehouse slab

Say a concrete contractor is saw-cutting control joints outdoors on a warehouse slab with a walk-behind saw, and two days later coring 40 penetrations indoors for the plumber with a handheld core drill. Here is how the office would set the job up.

  1. List each task in the job's exposure control plan: walk-behind saw cutting outdoors, core drilling indoors, and slab cleanup.
  2. Check whether each task and tool has a matching Table 1 row, copy the exact controls into the plan, and plan an exposure assessment for anything that does not match. Include water feed checks and any respirator required for the shift length.
  3. Check the equipment before the job: water tank, hoses, and nozzles on the saw; the core rig's water feed and vacuum.
  4. Plan cleanup with a HEPA vacuum and wet methods, and ban dry sweeping of the slurry dust.
  5. Name the foreman as competent person and record a short silica toolbox talk the morning of the cut.
  6. Track respirator days per worker. A finisher who wears a respirator on 30 or more days this year gets the medical exam offer.

The cost is mostly planning time and a few equipment checks. Pricing that time into the bid is easier when silica tasks show up in your general conditions and equipment line items instead of being absorbed by the crew.

Common silica compliance mistakes

  1. Assuming a task is on Table 1 when the specific tool or setting is not listed.
  2. Running wet methods without enough water flow, which quietly takes you off Table 1.
  3. No job-specific exposure control plan, or a plan that lists tasks the crew is not doing.
  4. Dry sweeping or blowing off with compressed air at the end of the day.
  5. Not counting respirator days, so nobody knows who is due for a medical exam.
  6. Forgetting about other trades nearby. Restricting access to the work area is part of the plan.

Templates and tools that help

Add silica tasks to your construction site safety plan, check controls during each jobsite safety inspection, and log saw and vacuum service in an equipment log template. Keep safety data sheets for the products you cut on file. If an inspector arrives, how to prepare for an OSHA inspection covers what they will ask for.

Smart Business Automator stores exposure control plans, training records, and subcontractor compliance documents with each job, so the plan for this project is one search away when a GC or inspector asks. See subcontractor compliance automation.

Frequently asked questions

What is the OSHA silica exposure limit for construction?

The permissible exposure limit is 50 micrograms of respirable crystalline silica per cubic meter of air, averaged over an 8-hour shift. Work where exposure will stay below 25 micrograms per cubic meter under any foreseeable condition falls outside the standard.

Do I have to do air monitoring for silica?

Not if the task is listed on Table 1 and you fully and properly use the listed controls. Tasks not on Table 1, or where you cannot follow its controls, require an exposure assessment by air monitoring or objective data.

Who needs a silica medical exam?

Workers required to wear a respirator under the silica standard for 30 or more days a year must be offered a medical exam at no cost within 30 days of assignment, and then at least every three years.

Can workers dry sweep silica dust?

Not where it could contribute to exposure, unless wet sweeping, HEPA-filtered vacuuming, or other low-exposure methods are not feasible.

Does a small contractor need a written silica plan?

Yes, if the work is covered by the standard. The rule requires a written exposure control plan describing the tasks, the controls for each, housekeeping, and how access is restricted, reviewed at least annually.

Sources

  1. 29 CFR 1926.1153: Respirable crystalline silica (Cornell LII)
Written and edited by

Maurice Francois writes and edits construction operations guides for Smart Business Automator. More from Maurice on the Scaling Legends podcast.

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