Silica Dust: OSHA's Table 1 for Cutting, Grinding and Drilling

Cut a concrete paver, grind a mortar joint or drill an anchor into block, and the dust that comes off carries crystalline silica. OSHA's silica standard for construction, 29 CFR 1926.1153, decides whether your crew needs a respirator for that work, and for most common tasks it answers with a single table. Here is how Table 1 works, task by task, what every covered employer has to do besides, and when the standard does not apply at all.

Why the rule exists

Crystalline silica is a common mineral in construction materials such as sand, stone, concrete, brick and mortar. Cutting, grinding, drilling or crushing them makes particles small enough to travel deep into the lungs. OSHA lists what they cause: silicosis, an incurable lung disease that can lead to disability and death, lung cancer, chronic obstructive pulmonary disease and kidney disease. OSHA's fact sheet puts the exposed construction workforce at about two million workers in over 600,000 workplaces.

OSHA published the standard on March 25, 2016. CPWR, the construction research center, notes that it was not enforced in construction until September 23, 2017, which is why its citation counts for silica begin in 2018.

When it does not apply

The standard covers all construction exposures except where an employee's exposure will remain below 25 micrograms per cubic meter of air, as an 8-hour average, under any foreseeable conditions (29 CFR 1926.1153(a)). OSHA's small entity guide treats a failure of your dust controls as foreseeable, so a task that stays low only because the controls work is still covered.

The guide gives examples of tasks expected to stay under that line when done apart from dustier work: mixing concrete for post holes, pouring concrete footers, slab foundations and foundation walls, and removing concrete formwork. It also speaks to the trades that drill now and then. For a worker drilling holes in concrete or masonry with a handheld drill for 15 minutes or less, with no other exposure that shift, the guide says the 8-hour exposure can reasonably be expected to stay under the threshold and the standard would not apply.

Two ways to comply

For each task listed in Table 1, you either fully and properly carry out the controls and respiratory protection the table specifies, or you assess and limit exposure yourself under paragraph (d) (29 CFR 1926.1153(c)(1)). The second route means measuring or otherwise establishing exposures and keeping them at or below the permissible exposure limit of 50 micrograms per cubic meter as an 8-hour average, with an action level of 25. The fact sheet sums up the table's advantage: employers who follow Table 1 correctly are not required to measure workers' exposure from those tasks and are not subject to the limit.

“Fully and properly” is a real test. The guide says the controls must be in place, properly operated and maintained, and understood by the people using them, and that large amounts of visible dust generally mean the controls are not working as they should.

Table 1, task by task

The common rows for residential trades, with the minimum respirator (by assigned protection factor, APF) for four hours or less of the task in a shift, and for more than four hours:

Each of these rows also requires operating and maintaining the tool by the manufacturer's instructions. The dust collectors need a filter of 99 percent or greater efficiency and the airflow the row sets: the tool maker's recommendation or more, or for grinders 25 cubic feet per minute per inch of wheel diameter. On the drill, jackhammer and grinder rows the collector also needs a filter-cleaning mechanism (for grinders, a cyclonic pre-separator also qualifies), so check the vacuum before you buy it. Indoors or in an enclosed area, the employer must also provide exhaust as needed to keep visible airborne dust from building up (29 CFR 1926.1153(c)(2)(i)).

APF 10 is the lowest level Table 1 calls for. OSHA's fact sheet gives as an example a NIOSH-certified filtering facepiece respirator that covers the nose and mouth, sometimes called a dust mask. Any required respirator brings the respiratory protection standard, 29 CFR 1910.134, with it: a respiratory protection program, and a medical evaluation before a worker is fit tested or wears the respirator.

How the four hours are counted

The clock covers the time spent on the task, whether done continuously or on and off. The guide's own examples: a worker who cuts and places bricks one at a time for four hours and then spends 30 minutes cleaning the saw has a task of four and a half hours, while a worker who cuts bricks for 15 minutes, lays them for two hours and then cuts for another 30 minutes has a task of 45 minutes. If a job you expected to take three hours runs past four, the respirator in the over-four-hours column is required as soon as that becomes evident. And when one worker does several Table 1 tasks that add up to more than four hours in a shift, the over-four-hours column applies to each of them (29 CFR 1926.1153(c)(3)).

Some examples, framed as examples:

• Say a siding crew cuts fiber-cement lap siding outdoors all day with a 7¼-inch saw hooked to a dust collector that meets the row. No respirator is required, however long the cutting runs. Move the saw into the garage and that row no longer covers the work, because it is outdoors only; indoors you would have to assess and limit exposure the other way. For more on the trade, see siding.
• Say a concrete contractor's helper cuts a slab outdoors with a water-fed handheld saw for three hours. No respirator. Five hours of jackhammering outdoors the next day needs APF 10 for the whole task, not just the fifth hour. See concrete.
• Say a mason tuckpoints a chimney for two hours. Even under four hours, tuckpointing requires APF 10; over four, APF 25. See masonry.
• Say a tile setter breaks out an old tile floor indoors with a chipping hammer. Indoors, that row calls for APF 10 from the first minute. OSHA's own sample written plan in its guide is for exactly this job: demolishing concrete and tile floors inside homes with a jackhammer. See tile.

What every covered employer must do

• A written exposure control plan describing the tasks that involve silica, the controls, work practices and respirators for each task, the housekeeping measures, and how you restrict access to keep others out of the dust. Review it at least once a year (29 CFR 1926.1153(g)).
• A competent person, someone able to spot silica hazards and with the authority to fix them, who makes frequent and regular inspections of job sites, materials and equipment to carry out the plan.
• Housekeeping limits. No dry sweeping or dry brushing where it could add to exposure, unless wet sweeping, HEPA vacuuming or other low-dust methods are not feasible; no compressed air to clean clothing or surfaces unless a ventilation system captures the dust cloud or no other method is feasible (29 CFR 1926.1153(f)).
• Medical exams for any worker the standard requires to wear a respirator for 30 or more days a year, where any part of a day counts as a day: within 30 days of the assignment and every three years after, including a chest X-ray and a lung function test, at no cost to the worker, with travel time paid.
• Training each worker can show they understand: the health hazards, the tasks that expose them, your controls, the competent person's name and the medical program. A copy of the standard must be readily available to them without cost.
• Records of any air monitoring, any objective data you rely on, and the medical surveillance.

For penalties assessed after January 15, 2026, OSHA's maximums are $16,550 per serious violation and $165,514 per willful or repeated violation. Before it comes to that, OSHA's On-Site Consultation Program offers small businesses free, confidential help that is separate from enforcement and does not result in citations or penalties, according to OSHA's fact sheet. Dust from older painted surfaces brings a separate rule; see EPA's lead paint rule. And for working at heights on the same jobs, see fall protection and the six-foot line.

General information, not legal or tax advice. Rules change and vary by state; check with the agency named above or a professional for your situation.