The silica standard: Table 1, the PEL, and when you need air monitoring

If you cut, grind, drill, or break concrete, brick, stone, or mortar, you are making respirable silica dust, and OSHA's silica standard says you have to control it, usually with water or a dust-collecting vacuum. The exposure limit is 50 micrograms per cubic meter of air averaged over 8 hours, and the standard, 29 CFR 1926.1153, gives you a shortcut called Table 1 that lets you skip air monitoring if you use the listed controls. Silica dust causes silicosis, an incurable lung disease, plus lung cancer and kidney disease, and the damage builds up silently over years. This is federal OSHA in 2026.‍‌​‌​​‌‌‌‌‌‌‌‌‌‌​​​​‌‌‌​​‌‌‌‌​‌​​‍

What silica is and why it matters

Respirable crystalline silica is the fine dust released when you work materials that contain quartz: concrete, mortar, brick, block, stone, tile, and many others. The particles are small enough to get deep into your lungs and scar them permanently, there is no cure, and the damage is done years before anything feels wrong. That is why the standard treats dust control as mandatory rather than optional, and why "just a bit of dust" is the wrong way to think about it.

What it does to you, how it is diagnosed, and what you can claim if it has already happened are covered properly in silica dust and your lungs. This page is about the other half: what the standard actually requires you to do on site.

The PEL and the Action Level

• Permissible Exposure Limit (PEL): 50 micrograms per cubic meter of air, averaged over an 8-hour shift. That is the legal ceiling on how much silica a worker can breathe.
• Action Level: 25 micrograms per cubic meter, the halfway point that triggers extra requirements like exposure monitoring and, in some cases, medical surveillance.

These are tiny amounts. You cannot judge them by eye, which is exactly why the standard leans on controls rather than guesswork.

Table 1 is the shortcut

Table 1 is the practical heart of the standard. It lists specific construction tasks paired with the dust controls, work practices, and respiratory protection required for each. If you fully and properly use the Table 1 controls for a task, you do not have to do air monitoring for it. That is the deal Table 1 offers: follow the recipe, skip the sampling.

Common Table 1 tasks and their controls:

• Handheld power saw cutting concrete or masonry: water delivery to the blade, or a blade shroud with a HEPA dust vacuum. Outdoors with a proper water feed, no respirator is required; indoors or in an enclosed area, one is, whatever the duration. The four-hour split is counted across all your Table 1 tasks in the shift, not per task, which is set out below.
• Handheld grinder on concrete or mortar: a shroud plus a HEPA vacuum, with respiratory protection.
• Jackhammer or chipping tool: wet methods or local exhaust ventilation, with respiratory protection.
• Rotary or core drilling: water or a dust collector with a close-capture shroud; an enclosed cab is preferred for larger rigs.

If you deviate from Table 1, or your task is not on it, you have to assess exposures by air sampling and keep them below the PEL some other way.

What "fully and properly" actually means

This is the phrase the whole bargain hangs on, and it is where the exemption is usually lost. Table 1 does not say "use water". It specifies the control, and it repeatedly adds a line requiring you to operate and maintain the tool in accordance with the manufacturer's instructions to minimize dust emissions. That clause is part of the control, not advice attached to it.

In practice that rules out a lot of what happens on site:

• A hose trickling near the blade is not an integrated water delivery system. The entry says a saw "equipped with integrated water delivery system that continuously feeds water to the blade". Continuously, and to the blade.
• A shop vac is not a dust collector. Where Table 1 calls for one, it specifies performance: the collector must provide the air flow recommended by the tool manufacturer, or greater, and for several entries a filter of 99% or greater efficiency, with the filter cleaning the standard describes. A general-purpose vacuum with a clogged bag meets none of that.
• Running the control badly is the same as not running it. A shroud held away from the surface, a water feed switched off because it is making a mess, a collector nobody has emptied. Partial use is not partial compliance; if the control is not being used as specified, you are outside Table 1 and back to air monitoring.

Indoors changes the answer

Several Table 1 entries give two different respirator answers for the same task with the same control, depending on where you do it. The handheld saw with a water feed is the clearest: used outdoors, no respirator is required; used indoors or in an enclosed area, an APF 10 respirator is. Same saw, same water, different requirement.

"Enclosed area" is not a formal room. A basement, a partly finished shell, a stairwell, inside a container, under a tented scaffold, all behave like enclosures because the dust has nowhere to go. If you have brought the work inside to keep it out of the weather, you may have changed what the standard requires of you without noticing.

The four-hour trigger counts your whole shift, not each task

This is the one that catches people who have read Table 1 carefully. The respirator requirements are split at four hours per shift, and it is natural to read that per task. It is not.

Under 1926.1153(c)(3), where a worker does more than one Table 1 task in a shift, you add them together. If the combined total is more than four hours, the "more than four hours" respiratory protection applies to each of those tasks, including the short ones. Under four hours combined, the shorter requirement applies to each.

So two hours on a saw and three hours on a grinder is five hours, not two separate under-four stints, and the heavier requirement applies to both. Counting task by task is how a firm ends up genuinely believing it is compliant while nobody on the crew is wearing what the standard asks for.

And a respirator is not something you can simply hand out. Putting a worker in one brings its own requirements before first use, which is a separate rulebook from the silica standard and a common gap in small firms that have bought the masks and stopped there.

Medical surveillance, the plan, and housekeeping

• Medical surveillance. You must offer it, at no cost, to any employee who has to wear a respirator on silica tasks for 30 or more days a year. Even a few minutes of respirator use on a given day counts as one day. It starts with an exam within 30 days of the first qualifying assignment and repeats at least every 3 years.
• Written exposure control plan. The employer needs a written plan describing the tasks that make silica, the controls used for each, and the housekeeping practices. Under 1926.1153(g)(4) a designated competent person has to make frequent and regular inspections of the job site, materials and equipment to implement it. That is an active job with a named person attached, not a document in a folder.
• What you carry home. Silica behaves like the other dusts you should not be taking off site in your clothes or your van, and the practical routine for that is in lead and asbestos in older buildings.
• Housekeeping. No dry sweeping or dry brushing where it kicks up silica if a wet or vacuum method is feasible, and never use compressed air to blow dust off unless it is captured. Blowing concrete dust around with an air line is a classic violation.

Common questions

What is the OSHA silica exposure limit?

The permissible exposure limit for respirable crystalline silica in construction is 50 micrograms per cubic meter of air, averaged over 8 hours, in 2026. There is also an action level of 25 micrograms per cubic meter that triggers extra requirements like monitoring. These are very small amounts you cannot judge by eye. Verify the current figures at osha.gov.

What is Table 1 in the silica standard?

Table 1 is a list of common construction tasks paired with the dust controls and respiratory protection required for each. If you fully and properly follow the Table 1 controls for a task, you do not have to do air monitoring for it. Deviate from Table 1, or take on a task that is not listed, and you have to assess exposures by air sampling instead.

Do I need a respirator when cutting concrete?

It depends on the task and the duration. For a handheld saw cutting concrete under Table 1, a respirator is required if you cut for more than 4 hours in a shift, on top of using water or a shrouded HEPA vacuum. For grinding, chipping, and jackhammering, respiratory protection is generally required. The dust control comes first; the respirator is the backup, not the main defense.

When is silica medical surveillance required?

When an employee has to wear a respirator for silica tasks 30 or more days in a year, the employer must offer medical surveillance at no cost. Even a few minutes of respirator use counts as a full day toward that total. It starts with a medical exam within 30 days of the first qualifying task and repeats at least every 3 years.

Can I use compressed air to clean up concrete dust?

No, not where it puts silica into the air, which blowing dry concrete dust almost always does. OSHA prohibits dry cleaning methods like compressed air and dry sweeping for silica when a wet method or a vacuum with a HEPA filter is feasible. Clean up with water or a HEPA vacuum instead.

The honest bit

• The 50 microgram PEL, the 25 microgram action level, and the 30-day medical surveillance trigger are federal OSHA in 2026 under 29 CFR 1926.1153. Verify current figures at osha.gov.
• About 22 states run their own OSHA program and can require more. See Working in Your State.
• Silicosis is permanent and incurable, so the controls are worth doing right every time. This is general guidance, not training or medical advice. For an exposure assessment or a medical exam, use a qualified industrial hygienist or physician.

How this site is funded →

Spotted something wrong or out of date? Email us at hello@kilnguides.co.uk.

In crisis? 988 Suicide & Crisis Lifeline 988 · Mental health support

How this site is funded →