Safety
Silica and silicosis in countertop fabrication: the risk, the materials and the rules
Why cutting stone, especially engineered quartz, causes silicosis, how much silica each material holds, what the disease does, and the bans and rules in the U.S., California and Australia.
, CEO, Stonify
Cutting, grinding and polishing stone releases respirable crystalline silica: dust fine enough to reach the deepest part of the lungs, where it causes silicosis, a permanent and incurable scarring of the lungs.
Engineered quartz is the biggest risk. It is roughly 90% crystalline silica, about twice as much as the silica-richest granites.
Cases keep rising. California alone had confirmed 644 cases of engineered-stone silicosis among fabrication workers, with 35 deaths, as of September 10, 2026.
The rules are tightening. In the U.S., OSHA limits exposure to 50 µg/m³ averaged over 8 hours. Australia banned engineered stone in July 2024, and California is moving toward a ban.
An installed countertop is not a hazard. The danger comes from cutting and grinding it.
What's changing in California right now (September 2026)
On September 16, 2026, Cal/OSHA released a draft emergency rule that would stop the manufacture and fabrication of artificial stone with more than 1% crystalline silica. According to reports on the draft:
Shops could not buy new slabs above 1% starting 60 days after the rule takes effect.
All fabrication of those slabs would stop 180 days after it takes effect.
If the Standards Board adopts it in October or November 2026, it could take effect around December 2026 or January 2027.
Public comments are open through September 30, 2026. Send them to Cal/OSHA at RS@dir.ca.gov.
It is still a draft, and details can change. California's full set of rules, including the SB 20 law already in force, is further down this page.
What crystalline silica is
Silica is silicon dioxide, one of the most common minerals on earth. In its crystalline form, mainly quartz, it makes up sand, most granite, quartzite and sandstone. Some of it also exists as cristobalite, a form that can appear when silica is heated. Amorphous (non-crystalline) silica, such as ordinary glass, behaves differently in the body and is not what the OSHA rule regulates.
Solid stone is harmless. The hazard starts when a blade, router bit or grinding wheel breaks the stone into dust. Most of that dust is coarse and settles or gets caught in the nose and throat. A fraction is respirable: particles around 10 micrometers and smaller, a small fraction of the width of a hair. These stay airborne for a long time, are invisible at harmful levels, and travel all the way to the air sacs of the lungs.
The International Agency for Research on Cancer classifies crystalline silica as a Group 1 human carcinogen (lung cancer). OSHA also lists silicosis, lung cancer, chronic obstructive pulmonary disease (COPD) and kidney disease as health effects of silica exposure.
What silicosis does
When silica particles lodge in the lungs, the body's immune cells try to clear them and fail. The resulting inflammation lays down scar tissue (fibrosis), which stiffens the lung and blocks oxygen transfer. The scarring keeps progressing even after exposure stops. There is no cure. Treatment manages symptoms with oxygen, medication and pulmonary rehab, and severe cases need a lung transplant.
Doctors describe three patterns, depending on how much dust a worker breathed and for how long:
Form | Typical exposure before disease | What it looks like |
|---|---|---|
Chronic | 10 or more years of lower exposure | Slow onset. The classic form in older quarry and foundry workers. Often mistaken for asthma or COPD at first. |
Accelerated | About 5 to 10 years of higher exposure | Faster progression. This is the form seen in many engineered-stone fabricators. |
Acute | Weeks to about 5 years of very heavy exposure | Rapid, severe and often fatal. |
Early symptoms are shortness of breath on exertion, a lasting cough and fatigue. By the time symptoms appear, damage is often advanced, which is why OSHA requires medical screening with chest X-rays and lung-function tests for exposed workers. Silicosis also raises the risk of tuberculosis, lung cancer and autoimmune diseases such as scleroderma and rheumatoid arthritis.
Why engineered quartz is the biggest risk
Engineered quartz is crushed quartz bound with polyester or similar resin and pressed into slabs. Because the filler is mostly quartz, the slab is mostly crystalline silica. Cutting or grinding it dry releases dust that is far richer in silica than granite dust.
Two other things make it worse in practice:
Volume. Quartz became the most common countertop material in many U.S. markets, so a typical shop now cuts far more of it than it did 15 years ago.
Work habits. Clusters of disease have been traced to shops where workers dry-ground edges and sink cutouts with handheld angle grinders, often without respirators, for years.
Researchers are still studying whether the resin and the particle shape add to the harm. The practical point for a shop is simpler: dust from engineered quartz carries roughly twice the silica of the dustiest natural granite, so every uncontrolled minute counts for more.
How much silica each material contains
These are approximate crystalline silica contents by weight. Actual values vary by product, quarry and color, so check the safety data sheet (SDS) for the specific slab.
Material | Approx. crystalline silica | Notes |
|---|---|---|
Engineered quartz (standard) | About 90% or more | Highest risk of common countertop materials |
"Low-silica" or reduced-silica quartz | Varies by product, from under 40% down to claims of under 10% or 1% | Lower, not zero. Check the SDS. |
Quartzite | Often above 90% | True quartzite is nearly pure quartz. Treat like engineered quartz. |
Sandstone | High, often well over 50% | Rare for countertops |
Granite and similar igneous stone | Varies widely, up to about 45% | Figures of "60 to 70% silica" count total silica, including silicate minerals that are not free crystalline silica |
Sintered stone | About 7 to 17% (one 2022 study) | Not silica-free |
Porcelain slab | Varies by product | Can contain quartz; check the SDS |
Marble, limestone | Usually very low | Some marbles have quartz veins |
Soapstone | Usually low | Varies by deposit |
Solid surface, laminate, wood | Essentially none | Different dust hazards (polymer and wood dust) |
Two lessons come out of this table. First, granite is not safe to dry-cut just because it has less silica than quartz. Up to 45% silica is still plenty to exceed OSHA's limit quickly. Second, porcelain and sintered stone are lower-silica, not no-silica, and cutting them still falls under the OSHA silica rule.
How many workers are affected
U.S. numbers come from state health departments and case reports, not from a national registry, so they undercount.
2019: CDC reported 18 cases of silicosis in engineered-stone fabrication workers in California, Colorado, Texas and Washington, including the first two U.S. deaths (MMWR, 2019).
2023: A study in JAMA Internal Medicine described 52 California fabrication workers with engineered-stone silicosis, 10 of whom had died. Most were Latino immigrant men, many diagnosed in their 30s and 40s.
2026: The California Department of Public Health (CDPH) counted 592 confirmed cases, 65 lung transplants and 31 deaths through June 2026 (published in NEJM Evidence in August 2026). By August 13 the total was 631 cases, 74 transplants and 35 deaths, and by September 10, 2026, it had reached 644 confirmed cases. About 98% of the workers were Latino, and the median age at diagnosis was 46.
The numbers keep rising partly because more cases are being found, and partly because disease from past exposure shows up years later. A worker exposed in 2018 may be diagnosed in 2027.
Inspections show how common overexposure has been. A CDPH analysis of Cal/OSHA inspections from January 2019 to February 2020, cited by NIOSH in 2026, found that 51% of inspected stone fabrication shops had at least one worker above the OSHA limit.
Similar outbreaks have been documented in Australia, Israel and Spain, all tied to engineered stone.
How exposure is prevented
The fix is well known and works when it is used every day. It follows the hierarchy of controls, which ranks methods from most to least reliable:
Substitution. Cut lower-silica materials where the customer is willing. This is why reduced-silica quartz, porcelain and sintered stone are growing.
Engineering controls. Wet cutting and polishing with continuous water at the tool, enclosed CNC machines, and local exhaust ventilation (dust extraction at the tool, such as a shroud connected to a HEPA vacuum). Water and extraction together work better than either alone.
Work practices. No dry cutting, no dry sweeping, no compressed air for cleanup. Clean up slurry before it dries, because dried slurry turns back into dust.
Respirators. Fit-tested respirators protect workers where the controls above are not enough. They are the last line, not the first.
Medical surveillance. Regular chest X-rays and lung-function tests find disease early and show whether controls are working.
The details, including what OSHA requires at each step, are in OSHA silica compliance.
U.S. federal rules
OSHA's respirable crystalline silica standard took effect in 2016, with enforcement for general industry from June 2018. It cut the old limits, roughly 100 µg/m³ for general industry and about 250 µg/m³ for construction, to a single permissible exposure limit.
Item | Value |
|---|---|
Permissible exposure limit (PEL) | 50 µg/m³ as an 8-hour time-weighted average |
Action level (triggers monitoring and medical surveillance) | 25 µg/m³ as an 8-hour time-weighted average |
Fabrication shops | General industry standard, 29 CFR 1910.1053 |
Cutting and grinding at the customer's site | Construction standard, 29 CFR 1926.1153 |
NIOSH recommended exposure limit (advisory) | 50 µg/m³, for up to a 10-hour day |
A µg/m³ (microgram per cubic meter) is a tiny amount. At the PEL you would not see any dust in the air. Visible dust means levels are likely many times the limit.
OSHA estimated when it issued the rule that it would prevent more than 600 deaths and 900 new silicosis cases a year across all industries. It has run a National Emphasis Program on silica since 2020, and in September 2023 it launched a focused inspection initiative on engineered-stone fabrication and installation. OSHA and NIOSH published a joint hazard alert on countertop fabrication back in 2015.
There is no federal ban on engineered stone as of September 2026.
Australia's ban
Australia is the first country to ban engineered stone outright. From July 1, 2024, it has been illegal under national work health and safety laws to manufacture, supply, process or install engineered stone benchtops, panels and slabs. From January 1, 2025, their import is also banned.
Key points of the Australian rule, per Safe Work Australia:
The ban covers artificial stone products containing 1% or more crystalline silica. Products marketed as "low silica" are still banned if they are at or above 1%.
Porcelain and sintered stone that contain no resin are excluded. A product labeled porcelain or sintered stone that contains resin and silica is treated as engineered stone.
Work on existing (legacy) engineered stone, such as removal, repair, minor modification or disposal, is still allowed with controls, and the regulator must be notified first.
The ban followed a wave of silicosis among young benchtop workers and a Safe Work Australia finding that exposure could not be reliably controlled across the industry. Australian law does not apply to U.S. shops, but the evidence behind it is the same.
California's engineered stone rules (as of September 2026)
California has the most cases in the U.S. and the strictest rules. This section describes the situation in September 2026. Several pieces are still changing, so check with Cal/OSHA (the Division of Occupational Safety and Health, dir.ca.gov/dosh) before relying on any date.
1. Cal/OSHA silica standard, Title 8 Section 5204 (in force). Cal/OSHA adopted emergency engineered-stone provisions in December 2023 and made the amended standard permanent on February 5, 2025. For high-exposure trigger tasks, meaning cutting, grinding, drilling, polishing and similar work on artificial stone with more than 0.1% crystalline silica or natural stone with more than 10%, plus the cleanup of their waste, the rule requires:
Effective wet methods designed to bring exposure below the action level.
No dry sweeping, no compressed air, and no rotating employees to dilute their exposure.
High-protection respirators, generally powered air-purifying respirators (PAPRs) in the APF 1000 class, with limited exceptions.
Regular exposure monitoring, training in a language workers understand, and regulated areas.
Employer reports to CDPH and Cal/OSHA within 24 hours of learning of a confirmed silicosis or silica-related lung cancer case.
2. SB 20, the Silicosis Training, Outreach and Prevention (STOP) Act (law). Signed on October 13, 2025. It writes the wet-methods requirement and the ban on dry methods for high-exposure tasks into state law. A violation can lead to an immediate order to stop work. Shops must train the workers who do these tasks and, from July 1, 2026, file a yearly attestation with Cal/OSHA that they have. The law also makes silicosis and silica-related lung cancer a "serious illness" under state workplace law, and requires CDPH to report each case to Cal/OSHA within three business days, after which Cal/OSHA must open an investigation. An early 2025 draft of the bill would also have required shop certification from July 2027 and limited slab sales to certified shops; those provisions were removed before it passed.
3. Proposed emergency ban (in public comment). On May 21, 2026, the Cal/OSHA Standards Board voted unanimously to grant a petition from physicians (Petition 609) to ban engineered stone. On September 16, 2026, Cal/OSHA released a draft emergency regulation that would prohibit manufacturing and fabricating artificial stone containing more than 1% crystalline silica. According to reports on the draft, shops could not acquire new slabs above 1% starting 60 days after the rule takes effect, and all fabrication of such slabs would stop 180 days after it takes effect. Public comments are open through September 30, 2026, and go to Cal/OSHA at RS@dir.ca.gov; the draft is posted on Cal/OSHA's silica advisory committee page. If the Standards Board adopts it at its October or November 2026 meeting, the rule could take effect around December 2026 or January 2027.
California also lists respirable crystalline silica under Proposition 65 as a chemical known to cause cancer.
Other states and lawsuits
No other U.S. state had banned engineered stone as of September 2026, though several have discussed bills or stepped up enforcement. More than 20 states run their own OSHA-approved state plans for private employers, which must be at least as protective as federal OSHA and can be stricter. Check with your state plan or federal OSHA office.
Litigation is growing fast. Hundreds of silicosis lawsuits have been filed in California against slab makers and distributors, and more than 600 nationwide by August 2026. Some of the verdicts so far:
August 2024, Los Angeles: a jury awarded a former fabricator about $52.4 million against several engineered-stone manufacturers and suppliers.
April 2026, Denver: a jury awarded a young fabricator $17.45 million but put more than 60% of the fault on the family shop where he worked. Shops carry their own risk.
August 2026, Los Angeles County: a jury returned a verdict of more than $47 million for the family of a fabricator who died of silicosis.
In Congress, a bill that would shield slab makers and sellers from these suits (H.R. 5437) passed the House Judiciary Committee in June 2026 but was not law as of September 2026. Employee claims against the employer usually go through workers' compensation. See insurance and risk.
For homeowners, designers and contractors
Is my quartz countertop dangerous? Not in normal use. An installed, undisturbed countertop does not release silica dust: using it, cleaning it and setting hot pans on it do not create respirable dust. The risk comes from cutting, grinding, drilling or polishing it, which includes repairs, modifications and tear-out, so that work belongs with a shop that uses wet methods and dust controls.
What about cutting done in my home? Installers often scribe edges, drill faucet holes or trim pieces on site. Done dry with an angle grinder, this can put silica dust into your house for a short time. Ask the installer to use wet tools or grinders with a dust shroud and HEPA vacuum. After install, clean any dust with a damp cloth or a HEPA vacuum, not a broom.
Should I avoid engineered quartz? That is a personal choice, and many buyers now factor worker health into it. Lower-silica options include reduced-silica quartz lines, porcelain, sintered stone, marble, soapstone and solid surface. Each has trade-offs in look, durability and price. See quartz, sintered stone and materials health and safety.
What to ask a fabricator:
Do you cut and polish everything wet, and do your grinders have water feed or dust extraction?
Do you have a written silica exposure control plan, and when was your air last tested?
Are your workers in a medical surveillance program and fit-tested for respirators?
How do you control dust when you cut on site?
In California: are you meeting Section 5204, and have you filed this year's SB 20 training attestation?
A good shop answers these without hesitation. See choosing a fabricator.
For fabricators
Treat every stone as silica-bearing until the SDS says otherwise. Quartzite and granite need the same controls as quartz.
Know which rule you are under. Shop work falls under 1910.1053. Site work falls under 1926.1153. Most shops need both.
Watch the material mix. A shift toward reduced-silica products lowers exposure but does not end the obligation to assess it. In Australia and in California's draft, the legal line is 1%.
Keep records for decades. Silicosis appears years after exposure. Exposure and medical records must be kept for 30 years or more.
Use free help. OSHA's On-Site Consultation Program gives small businesses a confidential hazard review with no citations.
Common mistakes
Believing a paper dust mask or an unfitted N95 makes dry cutting acceptable.
Assuming granite, quartzite or porcelain do not count.
Running the saw wet but finishing edges and sink cutouts with a dry grinder.
Sweeping or blowing off dried slurry at the end of the day.
Waiting for symptoms before getting workers screened.
FAQ
Can silicosis be cured or reversed? No. The scarring is permanent and usually keeps progressing after exposure ends. Stopping exposure early and treating symptoms slow the decline, and a lung transplant is the last resort.
Does wearing a respirator make dry cutting safe? Not as a plan. OSHA requires engineering controls such as water and extraction first, and respirators only where those are not enough. Dry cutting of engineered stone can produce levels too high for ordinary half-mask respirators.
Is low-silica quartz safe to cut? Safer, not safe. Less silica per gram of dust means lower exposure for the same work, but the OSHA rule still applies, and products at or above 1% crystalline silica would still be banned under Australia's rule and California's draft.
Do sintered stone and porcelain contain silica? Many do, at lower levels than engineered quartz. One 2022 study measured roughly 7 to 17% crystalline silica in sintered stone. Cut them wet with the same dust controls.
How long after exposure does silicosis show up? From a few years to decades. In California's engineered-stone cases, many workers were diagnosed in their 30s and 40s, which is young for this disease.
Does the Australian ban apply to U.S. shops? No. U.S. shops follow OSHA and any state rules. The ban matters because the same products and the same exposure evidence exist here.
Sources
OSHA, Respirable crystalline silica standards (29 CFR 1910.1053 and 1926.1153)
NEJM Evidence, engineered stone silicosis in California, CDPH surveillance (August 2026)
NIOSH Science Bulletin, Engineered stone and silicosis (January 2026)
California SB 20 (2025), Chapter 734, Statutes of 2025: enacted text
UCLA ERC, Standards Board votes to grant Petition 609 (May 2026)
PR Newswire, $17.45 million verdict in the first Colorado artificial stone silicosis case (May 2026)
Safety+Health, Bill that would shield stone slab manufacturers from silicosis lawsuits (June 2026)