OSHA Silica Table 1 Checker

What Table 1 is for

The construction standard gives an employer two ways to protect a worker on each task. Paragraph (c)(1) says that for each employee engaged in a task identified on Table 1, the employer shall fully and properly implement the engineering controls, work practices and respiratory protection specified for the task, unless the employer assesses and limits the worker's exposure under paragraph (d) instead. Paragraph (d) is the other route. It applies to tasks not listed in Table 1, or where the employer does not fully and properly implement the controls listed. Under (d) the employer must keep exposure at or below the permissible exposure limit (PEL) of 50 micrograms per cubic meter of air (µg/m³) as an 8-hour time-weighted average and assess it by air monitoring or objective data.

So Table 1 is a trade. Use exactly the controls in the row and the respirator in its column, and the standard treats the task as handled without air sampling. Change the controls, and the task is back under (d). The silica exposure calculator reads a monitoring result under (d), and objective data is the other way to assess one. The OSHA silica standard explained covers the whole rule.

How the respirator columns work

Table 1 gives each row two respirator columns: 4 hours a shift or less, and more than 4 hours a shift. Each entry is either None or a minimum assigned protection factor (APF): APF 10 or APF 25. Paragraph (c)(3) says how to pick the column when a worker does more than one Table 1 task. If the total time of all the Table 1 tasks in the shift is more than four hours, the respirator for each task is the one in the over-4-hours column. If the total is less than four hours, it is the 4-hours-or-less column for each.

Worked example: a laborer cuts block with a wet handheld saw outdoors for 2½ hours, then breaks out a slab with a wet jackhammer outdoors for 2 hours. Each task alone is under four hours, and both rows say None outdoors for 4 hours or less. Together they are 4½ hours, so both move to the over-4-hours column, which is APF 10 for each. The worker needs a respirator for both tasks. That is the case the tool shows when you add the two tasks.

The tool counts only the tasks done under Table 1 toward the four hours. A task done another way is assessed under (d) and needs whatever respirator that assessment calls for.

Tasks that are Table 1 tasks only outdoors

Four entries give controls "for tasks performed outdoors only": handheld saws cutting fiber-cement board (iii), drivable saws (v), dowel drilling rigs for concrete (viii), and handheld grinders for uses other than mortar removal when the grinder uses water (xii). Indoors, those tasks have no Table 1 entry, so the employer must assess exposure under (d). Several more rows change the respirator indoors: a wet handheld saw needs APF 10 indoors at any length of shift, against none outdoors for up to 4 hours.

The duties that come with the controls

Paragraph (c)(2) adds three things to every row. Indoors or in an enclosed area, provide a means of exhaust as needed to minimize the build-up of visible airborne dust. With wet methods, apply water at flow rates sufficient to minimize release of visible dust. Where the control is an enclosed cab or booth, it must be kept as free as practicable from settled dust, have working door seals and closing mechanisms and gaskets and seals in good condition, be under positive pressure from a continuous supply of fresh air, filter its intake air through a filter 95% efficient in the 0.3 to 10.0 µm range (MERV-16 or better, the standard says), and have heating and cooling.

Several rows also name a HEPA-filtered vacuum, for cleaning drilled holes or for the dust between passes of a floor grinder indoors. The standard defines a HEPA filter as at least 99.97% efficient in removing particles 0.3 micrometers in diameter. The HEPA rating OSHA requires for silica vacuums and whether a shop vac can handle silica dust go into which vacuums qualify.

Table 1 at a glance

The respirator each row requires, as the minimum APF, with its controls fully in place. "Outdoors only" means the row has no entry for indoor work.

Abrasive blasting is not on Table 1, so it falls under paragraph (d), and (d)(3)(ii) adds the other OSHA standards that apply to it, such as 29 CFR 1926.57 on ventilation.

Which respirator meets an APF

An APF is the level of protection a class of respirator is expected to give when used under a full respiratory protection program. 29 CFR 1910.134 Table 1 sets them. A half mask air-purifying respirator, which includes filtering facepieces and elastomeric half masks, is APF 10. A powered air-purifying respirator (PAPR) with a loose-fitting facepiece is APF 25, and so is a PAPR with a helmet or hood unless the maker has test evidence for 1,000. A full facepiece air-purifying respirator and a half mask PAPR are APF 50. Note 1 to that table lets an employer use a higher class than required. Paragraph (e)(2) of the silica standard requires a respiratory protection program under 1910.134 wherever a respirator is required, which means medical evaluation, fit testing and training.

When medical exams start

Paragraph (h)(1)(i) requires the employer to make medical surveillance available, at no cost, to each employee who will be required to use a respirator under the standard for 30 or more days a year. The first exam is due within 30 days of the first assignment, unless the worker had one meeting the standard in the last three years. It covers a medical and work history, a physical exam focused on the lungs, a chest X-ray read by a NIOSH-certified B Reader, a lung function test, and a test for latent tuberculosis. Exams repeat at least every three years, without the tuberculosis test. Count every day the standard requires a respirator, so a worker who needs APF 10 only on long shifts counts only those days.

What Table 1 does not change

Following Table 1 removes the exposure assessment for that task, and nothing else. The employer still needs a written exposure control plan under paragraph (g), with a competent person to inspect the site; the plan builder turns the tasks you checked here into one. Housekeeping rules still apply: no dry sweeping or dry brushing, and no compressed air, where they could add to exposure and a safer method is feasible. Workers still need training on the hazards, the tasks and the controls. And OSHA's silica National Emphasis Program inspects for all of it.

General information from the federal standard, not legal advice. States with their own OSHA-approved plans can have stricter rules, and California has its own silica standard. Check the current text before relying on it.
Sources: 29 CFR 1926.1153, Respirable crystalline silica (construction), Table 1 and paragraphs (c), (d), (e), (g) and (h); 29 CFR 1910.134, Respiratory protection, Table 1, Assigned Protection Factors; OSHA, Silica in construction.