Crystalline Silica

Silica is in sand, concrete, brick, block, stone, mortar, tile and engineered stone. Cutting, grinding, drilling, chipping or crushing these materials creates dust so fine you can’t see most of it. Breathing it causes silicosis, lung cancer, COPD and kidney disease. Silicosis can’t be cured, but it can be prevented.

• Construction
• General Industry
• Masonry
• Concrete
• California

What silica is

Crystalline silica (quartz is the most common form) is one of the most common minerals on earth. Large pieces are harmless. The danger is respirable silica: particles at least 100 times smaller than a grain of beach sand, small enough to get deep into your lungs. A visible dust cloud means a lot of silica, but dangerous levels can be present even when the air looks clear.

Check the Safety Data Sheet for the product you’re cutting. See Safety Data Sheets.

What silica does to your body

• Silicosis: silica particles scar the lungs, which get stiff and can’t move oxygen. Chronic silicosis usually appears 10 or more years after exposure. Heavy exposure can cause accelerated silicosis in 5 to 10 years, or acute silicosis in weeks to months, which is often fatal. Silicosis keeps getting worse even after exposure stops.
• Lung cancer: silica is a known human carcinogen.
• COPD: chronic bronchitis and emphysema that make breathing difficult.
• Kidney disease and autoimmune diseases such as rheumatoid arthritis.
• Tuberculosis: people with silicosis are much more likely to get TB.

Early silicosis may have no symptoms. Later signs include shortness of breath, a lasting cough, tiredness and chest pain. If you’ve worked around silica dust, tell your doctor about your work history.

Tasks that create silica dust

• Cutting concrete, block, brick, stone, pavers, tile and fiber cement siding with saws
• Jackhammering, chipping and grinding concrete and masonry
• Drilling and coring concrete, and drilling rock
• Tuckpointing and grinding out mortar
• Abrasive blasting with sand or on concrete and masonry. See Abrasive Blasting.
• Milling asphalt and concrete, crushing and demolition
• Fabricating engineered stone countertops. See Countertop Fabrication.
• Dry sweeping or blowing off dusty surfaces, and mixing dry concrete or mortar

The OSHA silica rules

OSHA has two silica standards: one for construction (29 CFR 1926.1153) and one for general industry and maritime (29 CFR 1910.1053).

• Permissible exposure limit (PEL): 50 micrograms per cubic meter of air (µg/m³), averaged over 8 hours.
• Action level: 25 µg/m³. At or above this level, employers must take certain steps such as regular exposure monitoring.
• Written exposure control plan describing the tasks that create silica dust, the controls, the respirators, and how access to dusty areas will be limited.
• Competent person (construction) who makes frequent inspections and puts the plan into practice.
• Housekeeping: no dry sweeping or dry brushing where it could contribute to exposure, unless wet sweeping or HEPA vacuums aren’t feasible. No compressed air for cleaning clothes or surfaces unless it’s used with ventilation that captures the dust.
• Training on the health hazards, the tasks that create dust, the controls and the medical surveillance program.

Table 1 (construction)

Table 1 lists 18 common construction tasks and the controls and respirators required for each. If an employer fully and properly follows Table 1 for a task, they don’t have to measure workers’ exposure for that task. Some examples:

Table 1 also requires the equipment to be used and maintained the way the manufacturer says: the water must keep flowing, the shroud must fit, and the dust collector filters must be cleaned. If you can’t follow every part of Table 1 for a task, the employer must measure exposures and control them below the PEL.

APF means “assigned protection factor,” how much a properly fitted respirator reduces what you breathe. A filtering facepiece (N95) or half-face elastomeric respirator is APF 10. A loose-fitting powered air-purifying respirator (PAPR) is APF 25, and a full-facepiece air-purifying respirator is APF 50. Any respirator with an APF at least as high as Table 1 requires is acceptable. See Respiratory Protection.

Medical exams

• In construction, workers who must wear a respirator for 30 or more days a year under the silica rule get a medical exam, paid for by the employer, within 30 days of starting that work and every 3 years after.
• The exam includes a medical and work history, a physical exam focused on the lungs, a chest X-ray, a breathing test and a TB test (at the first exam).
• In general industry, exams are required for workers exposed at or above the action level for 30 or more days a year.
• The doctor’s written opinion goes to you. The employer gets only limited information unless you agree to share more.

Engineered stone: a growing crisis

Engineered stone countertops can contain more than 90% silica. Workers who cut, grind and polish it, often dry, are developing severe silicosis in their 20s, 30s and 40s, and some have needed lung transplants or have died. Several states have adopted special rules for engineered stone fabrication, and California has an emergency rule with stricter requirements. If you work in a countertop shop, wet methods and proper respirators are essential. See Countertop & Engineered Stone Fabrication.

Protect yourself

• Use water: saws and grinders with water feed, wet drilling and misting. Keep the water flowing for the whole cut.
• Use vacuum dust collection: shrouds connected to a HEPA vacuum that meets the tool manufacturer’s airflow requirement.
• Wear the respirator your task requires, fit-tested and seal-checked every time. Be clean-shaven where the respirator seals.
• Position yourself upwind and away from other workers’ dust. Don’t work in another crew’s dust cloud.
• Clean up with HEPA vacuums or wet methods, never a broom or compressed air.
• Keep it off you: change out of dusty work clothes before getting in your vehicle, and wash work clothes separately.
• Don’t eat, drink or smoke in dusty areas.

Before you cut: checklist

• I know whether the material contains silica (check the SDS)
• My tool has working water delivery or a shroud and HEPA dust collector
• Water is flowing, or the vacuum is on and its filter is clean
• I have the right respirator, it fits, and I did a seal check
• Other workers are out of my dust, or protected
• I have a HEPA vacuum or wet method for cleanup

Last updated: October 1, 2026