Silica Dust in Flooring Work

Why this matters

A flooring crew makes silica dust in more places than it thinks. The wet saw is the obvious one and it is usually the cleanest. The bag of thinset dumped into a bucket, the cement board cut with a circular saw in the garage, the chipping hammer under the old tile and the cup wheel on a slab ridge are where the exposure actually happens, mostly indoors, in a closed room, with the installer's face two feet from the source. Silicosis, lung cancer and kidney disease show up years later, there is no cure, and the dust that causes them is too fine to see.

This card maps silica onto the flooring tasks that make it and the control each one needs. The standard itself, its numbers and its two compliance paths, belongs to 'Respirable Crystalline Silica and the Construction Standard'. Setting up each Table 1 row on the tool is 'How to Follow Table 1 When You Core or Grind Concrete'. Neither is re-taught here.

Which standard a flooring crew works under

Installing, removing and repairing floors in an existing building is construction work (alteration and repair), so a crew on a job site works under 29 CFR 1926.1153 and its Table 1. Cutting stone or tile in your own shop for later install is general industry, 29 CFR 1910.1053, which has no Table 1. State-plan states can add to the federal text; where yours has its own silica standard, read it alongside this card.

The standard binds you as an employer toward your employees. The homeowner in the next room is outside OSHA's reach, and your ordinary duty of care to them comes to the same practical answer: keep them, their pets and their HVAC out of the dust.

Two mechanics from the construction standard decide most flooring days, and both are stated in full in the owning card:

• A Table 1 task fully and properly implemented needs no exposure measurement. Partially implemented (the wrong vacuum, the water turned off, no exhaust indoors) means the task drops to exposure assessment.
• More than 4 hours of Table 1 tasks in a shift, added across all of them, moves every Table 1 task that day to its more-than-4-hours respirator column, per 1926.1153(c)(3).

The flooring task map

The respirator column below is the row's requirement in substance. Read the row itself in the current text before you rely on it, because a row's conditions (water flow, airflow, indoor exhaust) are part of the requirement, not footnotes.

Three common flooring tasks have no row at all. Mixing thinset, grout, patch and self-leveler from powder; cutting glass-mesh cement backer board with a power saw indoors; and dry sweeping. The first two fall to exposure assessment (path two in the owning card); the third is prohibited where it could contribute to exposure, unless wet sweeping, HEPA vacuuming or another low-dust method is not feasible, under the housekeeping paragraph, 1926.1153(f).

On backer board specifically: fiber-cement board has its own row (blade 8 inches or smaller, outdoors only, with the saw's dust collection), and glass-mesh cement board is not fiber-cement. Indoors there is no row that fits a dry power cut on either. The control that beats every row is the one that makes no dust: score with a carbide scoring knife and snap, and cut holes with a carbide hole saw at low speed under a vacuum shroud. The same logic applies to tile. A manual rail cutter scoring and snapping a straight cut is not a Table 1 task because it makes almost nothing to breathe.

What looks like a control and is not

A shop vacuum with a paper filter. It passes the respirable fraction straight through its exhaust and blows it around the room at floor level. A grinder shroud on a shop vac is not the Table 1 row, so the task drops to assessment.

A box fan in a window. Indoors, Table 1 rows require exhaust as necessary to minimize visible dust (1926.1153(c)(2)), and a fan pulling air out of the work room toward the outdoors helps with that. It is not source capture, and a fan blowing into the room spreads the dust through the house.

Water that is allowed to dry. Wet cutting and wet grinding leave slurry. Dried slurry on the floor, the saw tray and boots becomes fine dust the next time somebody walks through it. Clean slurry up wet before it dries, and empty the saw tray outdoors.

A filtering facepiece with no program behind it. A filtering facepiece can carry an assigned protection factor of 10 under 29 CFR 1910.134, so it can meet an APF 10 requirement. It counts only when worn under a written respiratory protection program with medical evaluation and fit testing. Without the program, the crew does not do the task that required the respirator.

The absence of visible dust. The limit is a quantity no one can see. Visible dust is a sign the controls are not working and a limit may be exceeded; a clean-looking room is no proof that it is not.

Mixing from powder: the task with no row

Portland-based thinset, grout, patch and self-leveler carry quartz sand. Most of the airborne dose comes in the first seconds, when the bag is cut, dumped and the paddle first bites. Because mixing is not a Table 1 task, the shop's exposure control plan has to cover it with objective data or air monitoring, and the plan should name the controls:

• Add powder to the measured water, not water to powder, and pour from low with the bag close to the bucket rim.
• Start the paddle at low speed until the powder is wetted, then bring it up to the maker's mixing speed.
• Mix outdoors or at the doorway of the work room with exhaust pulling away from the house, and never in the customer's living space or beside a return grille.
• Fold and bag empties instead of shaking them out.

The other route is skin. Wet portland mixes are strongly alkaline and can burn skin under a kneepad or a cuff over a few hours, and the chromium compounds in cement cause allergic dermatitis that does not go away. Wear waterproof gloves with cuffs, long sleeves and eye protection when mixing and back-buttering, wash skin with clean water and a pH-neutral soap, and if mix gets in an eye, flush with clean water for at least 15 minutes and get medical attention if it still hurts after flushing.

Demolition: silica, and what silica controls do not cover

Tearing out tile is chipping, and chipping indoors needs a respirator at any duration under its row. The bigger mistake on demolition is treating a silica setup as a general dust setup. Under old tile there may be a black cutback adhesive or an older resilient layer, and any resilient floor or black adhesive of unknown age is presumed to contain asbestos until tested. A shrouded hammer on a HEPA extractor does not make chipping asbestos-containing mastic acceptable; it is still disturbance of a regulated material, and the work stops until the test result is in. See 'Nine-Inch Floor Tile and Black Mastic' and 'Asbestos in Old Resilient Floors and Adhesive'.

Painted baseboard in a pre-1978 home is a lead question, not a silica one, and prying it off is a disturbance under 'EPA Lead RRP Rule for Contractors'.

Worked example: one kitchen, one shift, two installers

A 180 sq ft kitchen on a slab. The old ceramic tile comes up, one ridge in the slab gets ground, and new porcelain is cut and set. The lead and the helper split the shift like this.

The lead's shift:

• Chipping tile and thin-set mortar: 2.5 hours, indoors, demo hammer with a shroud on a HEPA extractor. Row: chipping tools. Respirator: APF 10 indoors at any duration.
• Grinding one ridge: 0.5 hour, 5 inch cup wheel, shroud on the same extractor. The row needs at least 25 cfm per inch of wheel, so 25 x 5 = 125 cfm. The extractor is rated at 150 cfm with a 99 percent filter and a filter-cleaning mechanism, so it meets the row.
• Cutting tile on the wet saw: 1.5 hours. Row: stationary masonry saws. No respirator.

Table 1 total for the lead: 2.5 + 0.5 + 1.5 = 4.5 hours, which is over 4. Under 1926.1153(c)(3) every task moves to its over-4-hours column. The chipping and the wet saw do not change (APF 10 and none in both columns). The grinding changes: shrouded indoors is none up to 4 hours and APF 10 over 4, so the half hour of grinding now requires the respirator too. In practice the lead keeps the same half mask on from chipping through grinding, and that shift is a required-respirator day toward the 30-day medical surveillance trigger.

The helper's shift:

• Wet saw: 2.0 hours. Table 1 total 2.0, under 4. No respirator for the saw.
• Mixing thinset: about 0.5 hour across the day. No row. The shop's exposure control plan, built on its own air sampling for bag dumping, requires an APF 10 half mask during dumping and the first minute of mixing. Because that requirement comes from the shop's assessment under the standard, it counts as a required day too.
• HEPA-vacuuming slurry and debris: housekeeping, done wet or by HEPA vacuum, never by broom.

What would change the answer.

• If the extractor had been a shop vacuum, the grinding would no longer be a Table 1 task at all, and the lead's half hour would need an exposure assessment rather than a column lookup.
• If the chipping had run 1.5 hours instead of 2.5, the lead's total would be 1.5 + 0.5 + 1.5 = 3.5 hours, under 4, and the grinding would need no respirator. The chipping still would, because its indoor requirement is APF 10 in both columns.
• If the helper had cut the backer board with a circular saw indoors instead of scoring it, that task would have no row, and the shop's plan would need data for it before anyone did it.

Housekeeping and the customer's house

Clean up by HEPA vacuum or wet methods; no dry sweeping and no compressed air where either could contribute to exposure, per 1926.1153(f), which allows those methods only under the narrow conditions it states. Seal the work room's supply and return grilles with plastic and tape before chipping or grinding, and, where the customer agrees, turn the forced-air system off for the dusty hours so it cannot pull dust into the ducts. That is an isolation, so it gets a restore: at the end of the day, remove the plastic, turn the system back on, confirm air is moving at a register in the work room, and tell the customer if the filter needs changing because dust reached it. Containment and floor protection are owned by 'The Flooring Job Site Protection SOP'.

References

• 29 CFR 1926.1153, Respirable Crystalline Silica (construction), including Table 1 and paragraphs (c) and (f); 29 CFR 1910.134, Respiratory Protection.
• See related: Respirable Crystalline Silica and the Construction Standard
• See related: How to Follow Table 1 When You Core or Grind Concrete
• See related: The Silica Exposure Control Plan SOP
• See related: Asbestos in Old Resilient Floors and Adhesive