Respirable Crystalline Silica and the Construction Standard

Why this matters

Crystalline silica is quartz and its relatives, and it is in sand, concrete, mortar, brick, tile, stone and a long list of products that do not look like rock. Cutting, grinding, drilling or breaking those materials makes dust fine enough to reach the deep lung, where it scars tissue for good. The diseases are silicosis, lung cancer, chronic obstructive lung disease and kidney disease, and silicosis has no cure. OSHA rewrote the rule in 2016 and it is one of the few exposure standards written with a field-ready shortcut, Table 1, built for exactly the short, varied tasks residential trades do. This card owns the standard for the library: what it requires, who it reaches, and how its two compliance paths differ.

Scope: which standard reaches your work

There are two silica standards with the same numbers and different machinery.

• 29 CFR 1926.1153 covers construction work. Coring a foundation for a line set, chasing masonry for a conduit run, drilling a slab for a termite treatment, breaking a floor for a drain repair and cutting pavers for a walkway all sit here when they are part of construction, alteration or repair.
• 29 CFR 1910.1053 covers general industry, including maintenance work and shop fabrication such as cutting countertops in a shop. It has no Table 1, and its medical surveillance trigger is exposure at or above the action level for 30 or more days a year, rather than respirator use.

The construction standard does not apply where the employer has objective data showing that exposure will remain below 25 micrograms per cubic meter as an 8-hour time-weighted average under any foreseeable conditions, per 1926.1153(a). That exemption carries a burden: "it was a small hole" is not objective data. For short-duration work this is where most shops assume they are exempt and are not.

State plans can add to this. California, for example, layered additional requirements onto its own silica standard for work on engineered stone, starting with an emergency standard at the end of 2023; check the current text, because that rule has been readopted and revised since. If your shop works in a state-plan state, read that state's version alongside the federal one. This card is an operational summary, not legal advice.

The two numbers

Both standards set a permissible exposure limit of 50 micrograms per cubic meter of air and an action level of 25, each calculated as an 8-hour time-weighted average; in construction the PEL sits at 1926.1153(d)(1). Fifty micrograms in a cubic meter of air is a quantity you will never see. A cubic meter is roughly the air in a closet a little over three feet on a side, and the limit is a speck of dust spread through all of it. That is why visible dust is a reliable sign the limit is being exceeded and its absence is no proof that it is not. See related: Dose, Route, and the Exposure You Cannot See for how a time-weighted average and an action level work.

Two ways to comply in construction

Path one: Table 1, at 1926.1153(c). Table 1 lists 18 common construction tasks and, for each, an engineering control and work practice plus the respirator required, split by whether the task runs up to 4 hours or more than 4 hours in the shift, and in some rows by indoors versus outdoors. An employer who fully and properly implements the row for a task does not have to measure exposure for that task. Three conditions that reach service work travel with it in 1926.1153(c)(2) and (c)(3) (a fourth covers enclosed cabs and booths on heavy equipment):

• Indoors or in an enclosed area, provide exhaust as necessary to minimize the accumulation of visible airborne dust.
• With wet methods, apply water at a flow rate sufficient to minimize the release of visible dust.
• If an employee does more than one Table 1 task in a shift and the total of all of them exceeds 4 hours, the respirator for each task is the one listed for more than 4 hours.

Path two: alternative exposure control methods, at 1926.1153(d). For a task not in Table 1, or a task done without its full Table 1 control, the employer must assess each employee's exposure, either by air monitoring or by objective data, and keep it at or below the PEL using engineering and work practice controls first, with respirators where those cannot get it down. Under the scheduled monitoring option, a result at or above the action level but at or below the PEL is repeated within 6 months, and a result above the PEL within 3 months. Results go to the employee in writing.

The practical difference is large. Table 1 costs a shroud, a vacuum and a respirator where the row asks for one. Path two costs an industrial hygienist, sampling pumps, a lab, and a monitoring calendar.

The other duties both paths carry

• Written exposure control plan, 1926.1153(g). Describes each task that involves exposure, the controls and respirators used for each, the housekeeping measures, and the procedures used to restrict access to the work area where needed, including from other employers. It is reviewed at least annually and made available to employees. See related: The Silica Exposure Control Plan SOP.
• Competent person, 1926.1153(g)(4). The plan designates someone to make frequent and regular inspections of job sites, materials and equipment to implement it. In a small shop this is usually the owner or a lead tech, and the role needs the authority to stop work.
• Respirators, 1926.1153(e). Where Table 1 or an assessment requires one, it is worn under a written program per 29 CFR 1910.134, with medical evaluation, fit testing and training.
• Medical surveillance, 1926.1153(h). Required for each employee who will be required by the standard to wear a respirator for 30 or more days a year. An initial exam within 30 days of assignment (unless one meeting the standard was done in the past 3 years), then at least every 3 years, by a physician or other licensed health care professional. It includes a chest X-ray, a breathing test (spirometry), and a tuberculosis test at the initial exam. The employer gets a written opinion limited to what the standard allows, not the employee's medical record.
• Housekeeping, 1926.1153(f). No dry sweeping or dry brushing where it could contribute to exposure, unless wet sweeping, HEPA vacuuming or other methods are not feasible. No compressed air to clean clothing or surfaces unless it is used with a ventilation system that captures the dust cloud, or no alternative is feasible.
• Training and records. Hazard communication and task training under 1926.1153(i); exposure and medical records kept under 29 CFR 1910.1020, which sets the duration of employment plus 30 years for medical records and 30 years for exposure records. See related: The Exposure and Medical Records SOP.

One gate, two outcomes: two crews on the same Tuesday

The gate is the same for both crews: is the task in Table 1, and is its row fully and properly implemented?

Crew A, outdoors. A tech cuts a concrete pad back by about 18 inches with a handheld power saw using integrated water for 3 hours, then cores two 4 inch holes through a poured foundation wall with a rig-mounted core drill fed with water for 2 hours.

• Both tasks are Table 1 rows, both with water as the listed control. Gate passes, so no exposure assessment is required.
• The handheld saw row outdoors calls for no respirator up to 4 hours and an APF 10 respirator beyond 4 hours. The rig-mounted core drill row calls for none.
• Shift total of Table 1 tasks: 3 hours plus 2 hours is 5 hours, which exceeds 4. Under 1926.1153(c)(3) each task takes its more-than-4-hours column, so the saw work now requires an APF 10 respirator, even though the saw itself ran only 3 hours.
• That respirator day counts toward the tech's 30-day medical surveillance tally.

Crew B, indoors. A tech grinds a high spot off a basement slab for a flooring job with a handheld grinder, a shroud, and a general-purpose shop vacuum with a standard paper filter.

• The grinder row with a shroud requires a dust collector providing at least 25 cubic feet per minute of airflow per inch of wheel diameter, with a filter of 99 percent or greater efficiency and a cyclonic pre-separator or filter-cleaning mechanism. A shop vacuum with a paper filter does not meet that. The row is not fully implemented, so the gate fails and the task falls to path two.
• Path two means assessment. Say a personal air sample over the 6 hours the tech spent in the basement reads 140 micrograms per cubic meter, and the other 2 hours of the shift were outdoors with no exposure. The 8-hour TWA is 140 times 6, which is 840, divided by 8, which is 105 micrograms per cubic meter. That is above the PEL of 50, by a factor of 105 divided by 50, which is 2.1.
• Above the PEL, the employer must first apply feasible engineering controls, here the correct vacuum. Until then the tech wears a respirator whose assigned protection factor exceeds 2.1, so an APF 10 half mask under the program covers it, and the monitoring repeats within 3 months.

The lesson in the pair. The same shroud on the same grinder, with the vacuum the row asks for, would have passed the gate with no sampling. The shop vacuum turned a Table 1 task into a monitoring obligation and a respirator day. The equipment requirement in the row is the control, not a suggestion. See related: How to Follow Table 1 When You Core or Grind Concrete for setting up each row.

What changes the answer

• The task is not in Table 1. Abrasive blasting, or most demolition with a sledge or pry bar, are not rows, so path two applies from the start. Cutting engineered stone on site can fit the handheld saw or grinder rows only with their full controls; dry-cutting it fits nothing.
• The row's conditions are not met. A water feed that leaves visible dust, an indoor task with no exhaust, or a vacuum below the airflow figure all fail the gate, even when the right tool is on the job.
• It is shop work. Fabrication in your own shop is general industry under 1910.1053, with no Table 1 and an action-level trigger for medical surveillance. Read the general-industry text before applying anything above.
• A state plan has its own rule. A state-plan state may layer additional requirements on top of the federal text, as California has for engineered stone. Where yours does, its version governs for work in that state.

References

• 29 CFR 1926.1153, Respirable Crystalline Silica (construction), including Table 1 and paragraphs (a), (c) through (i).
• 29 CFR 1910.1053, Respirable Crystalline Silica (general industry).
• 29 CFR 1910.134, Respiratory Protection; 29 CFR 1910.1020, Access to Employee Exposure and Medical Records.
• OSHA's Small Entity Compliance Guide for the Respirable Crystalline Silica Standard for Construction.
• See related: Silica in Materials You Might Not Expect; The Hierarchy of Controls on a Service Call.