Respirable Crystalline Silica for Construction Workers

What silica is and what it does

Respirable crystalline silica is quartz, cristobalite and/or tridymite contained in airborne particles that are determined to be respirable by a sampling device designed to meet the size-selective sampler characteristics in ISO 7708:1995. The rule covers silica exposure in construction work, except where exposure will stay below 25 micrograms per cubic meter of air (8-hour average) under any foreseeable conditions.

Health hazards

Your employer's training must address at least these hazards of silica:

Tasks that make silica dust

OSHA's Table 1 lists common tasks on materials containing crystalline silica, including using stationary masonry saws, handheld power saws, walk-behind saws, rig-mounted core saws or drills, handheld and stand-mounted drills, jackhammers and handheld powered chipping tools, handheld grinders (including for tuckpointing), milling machines and floor grinders, crushing machines, and heavy equipment that abrades or fractures silica-containing materials. You must be able to name the specific tasks at your workplace that can expose you.

Reference: 29 CFR 1926.1153(b) "Respirable crystalline silica" · 29 CFR 1926.1153(a) · 29 CFR 1926.1153(i)(1) · 29 CFR 1926.1153(i)(2)(i)(A) · 29 CFR 1926.1153(i)(2)(i)(B) · 29 CFR 1926.1153(c)(1) Table 1

Table 1: the controls are part of the tool

For each task listed on Table 1, your employer must fully and properly put in place the engineering controls, work practices and respiratory protection Table 1 specifies for that task, unless the employer instead assesses and limits your exposure another way the rule allows.

Examples from Table 1

• Stationary masonry saws and handheld power saws: use a saw equipped with an integrated water delivery system that continuously feeds water to the blade. Handheld saws for cutting fiber-cement board (blade diameter of 8 inches or less) have their own Table 1 entry: outdoors only, with a commercially available dust collection system.
• Handheld and stand-mounted drills: use a drill with a commercially available shroud or cowling with a dust collection system. The dust collector must provide the manufacturer's recommended air flow or greater, with a filter of 99% or greater efficiency and a filter-cleaning mechanism. Use a HEPA-filtered vacuum to clean holes.
• Many Table 1 entries also say: operate and maintain the tool according to the manufacturer's instructions to minimize dust emissions.

Make the controls work

• Wet methods: apply water at flow rates sufficient to minimize release of visible dust.
• Indoors or enclosed areas: provide a means of exhaust as needed to minimize the build-up of visible airborne dust.

Reference: 29 CFR 1926.1153(c)(1) · 29 CFR 1926.1153(c)(1) Table 1 · 29 CFR 1926.1153(c)(2)(i) · 29 CFR 1926.1153(c)(2)(ii)

Enclosed cabs and booths

Some Table 1 controls rely on an enclosed cab or booth, for example on drill rigs, crushers and heavy equipment. When one is used, the employer must make sure it:

• Is kept as free as practicable from settled dust
• Has door seals and closing mechanisms that work properly
• Has gaskets and seals in good condition and working properly
• Is under positive pressure from a continuous delivery of fresh air
• Has intake air filtered through a filter 95% efficient in the 0.3–10.0 µm range (e.g., MERV-16 or better)
• Has heating and cooling

Reference: 29 CFR 1926.1153(c)(2)(iii)(A) · 29 CFR 1926.1153(c)(2)(iii)(B) · 29 CFR 1926.1153(c)(2)(iii)(C) · 29 CFR 1926.1153(c)(2)(iii)(D) · 29 CFR 1926.1153(c)(2)(iii)(E) · 29 CFR 1926.1153(c)(2)(iii)(F)

Read the respirator columns

For each task, Table 1 lists the required respiratory protection and minimum assigned protection factor (APF) in two columns: 4 hours or less per shift and more than 4 hours per shift. Some tasks need none; others need APF 10 or more. For example, tuckpointing with a shrouded grinder needs APF 10 for 4 hours or less and APF 25 for more than 4 hours.

Doing more than one Table 1 task in a shift

Add up the time on all your Table 1 tasks that shift. If the total is more than four hours, use the respirator listed for more than four hours for each task. If the total is less than four hours, use the respirator listed for less than four hours.

Your employer's part

Where a respirator is required, your employer must provide an appropriate respirator that complies with 29 CFR 1910.134, and run a respiratory protection program under that standard.

Reference: 29 CFR 1926.1153(c)(1) Table 1 · 29 CFR 1926.1153(c)(3) · 29 CFR 1926.1153(e)(1) · 29 CFR 1926.1153(e)(2)

No dry sweeping, no blowing off

So the normal way to clean silica dust is wet sweeping or a HEPA-filtered vacuum, not a dry broom or an air hose.

Reference: 29 CFR 1926.1153(f)(1) · 29 CFR 1926.1153(f)(2) · 29 CFR 1926.1153(f)(2)(i) · 29 CFR 1926.1153(f)(2)(ii)

What your employer must have and tell you

The written exposure control plan

Your employer must have and follow a written plan that describes at least: the tasks that involve silica exposure; the engineering controls, work practices and respirators used for each task; the housekeeping measures; and the procedures to restrict access to work areas when necessary, including exposures created by other employers. You can ask to see and copy it.

The competent person

Your employer must designate a competent person to make frequent and regular inspections of job sites, materials and equipment to carry out the plan. You must know who that person is.

Air monitoring results

If your employer measures exposure instead of following Table 1, it must, within five working days after completing an exposure assessment, notify you in writing of the results or post them where all affected employees can see them. You or your representative must get a chance to observe the monitoring.

Your employer must also make a copy of the silica standard readily available to you without cost.

Reference: 29 CFR 1926.1153(g)(1) · 29 CFR 1926.1153(g)(1)(i) · 29 CFR 1926.1153(g)(1)(ii) · 29 CFR 1926.1153(g)(1)(iii) · 29 CFR 1926.1153(g)(1)(iv) · 29 CFR 1926.1153(g)(3) · 29 CFR 1926.1153(g)(4) · 29 CFR 1926.1153(i)(2)(i)(E) · 29 CFR 1926.1153(i)(2)(ii) · 29 CFR 1926.1153(d)(2)(vi)(A) · 29 CFR 1926.1153(d)(2)(vii)(A)

Medical exams

• If you will be required to wear a respirator under the silica rule for 30 or more days per year, your employer must make medical surveillance available to you at no cost, at a reasonable time and place.
• An initial (baseline) exam must be made available within 30 days after initial assignment, unless you had an exam meeting the rule within the last three years.
• Periodic exams are made available at least every three years, or more often if the licensed health care professional recommends it.
• The licensed health care professional explains your results to you and gives you a written medical report within 30 days of each exam.

Reference: 29 CFR 1926.1153(h)(1)(i) · 29 CFR 1926.1153(h)(2) · 29 CFR 1926.1153(h)(3) · 29 CFR 1926.1153(h)(5)