Why it matters

Silica dust is too fine to see. It goes deep into the lungs and stays there. Over years it scars the lung tissue. This is silicosis. It cannot be reversed, and it keeps getting worse after exposure stops.

Silica dust also causes lung cancer and chronic lung disease. Very heavy exposure can bring silicosis on much faster.

Workers rarely feel harm on the day. By the time they cough and lose breath, the damage is done. That is why the controls have to work every day, not just when the dust looks bad.

Where the dust comes from

Silica is in sand, stone, concrete, mortar, brick, tiles and many other building materials. It is harmless in a solid block. The danger starts when power tools turn it into fine dust.

The more energy a tool puts in, the more dust it makes. Cut-off saws, grinders, breakers and grit blasting make a lot of dust very fast. Enclosed rooms let it build up. Long jobs and the same task day after day add to the dose.

  • Cutting kerbs, blocks, paving and tiles with a cut-off saw.
  • Chasing walls and raking out mortar.
  • Scabbling, grinding and polishing concrete.
  • Drilling and coring concrete and masonry.
  • Breaking and hacking during demolition and renovation.
  • Dry sweeping and blowing dust off with compressed air.

Order of controls

  • Eliminate. Design out cutting. Order materials cut to size, plan cable runs to avoid chasing, and use cast-in fixings.
  • Substitute. Use a lower-energy method, such as a block splitter instead of a saw, or direct fastening instead of drilling. Use silica-free abrasives for blasting.
  • Engineer. Water suppression or on-tool extraction on every dusty tool. Screen off the work area. Ventilate enclosed spaces.
  • Administer. Keep other people away, rotate workers on long dusty tasks, train the crew, supervise the method, and monitor the air.
  • Personal protection. A respirator suited to the dust, fit-tested to the wearer. Work clothes that do not hold dust.

Water and extraction done right

Water works only if it reaches the cutting point the whole time. Wetting the material first and then cutting dry does not work. Check the water tank, the flow and the hose before each job.

On-tool extraction pulls the dust away as it forms. The tool, the hood, the hose and the extraction unit all have to match. Use an industrial unit rated for fine dust, such as an H or M class unit. A household or general shop vacuum is not enough.

Check the controls are working. If the area still looks dusty, they are not. Empty and change filters as the maker says, and fix damaged hoods and hoses before use.

Outdoors is not safe by default

Do not assume the open air will carry dust away. A cut-off saw outdoors can still give the operator a heavy dose in minutes.

Respirators

Water and extraction rarely remove enough dust on their own for the heavier tasks. Most dusty jobs need a respirator as well. Choose one rated for the amount of dust. UK guidance asks for an assigned protection factor of 20 for most construction dust. That means the wearer breathes a twentieth of the dust in the air.

A tight-fitting mask only works if it seals. Fit-test each worker on the model they will wear. Wearers must be clean-shaven where the mask meets the face. For jobs over an hour without a break, consider powered respirators. They are easier to wear for long periods.

Store respirators clean. Change disposable masks and filters as the supplier says.

The loose surgical mask

Surgical masks and loose dust masks do not stop fine silica. A beard under a tight-fitting mask breaks the seal. Neither counts as protection.

Clean-up and air monitoring

Dust that settles on floors and ledges gets stirred up again. Clean it up with a suitable vacuum or by wetting it down. Never sweep dry or blow it off with compressed air. That puts the dust straight back in the air, often into someone else's face.

Air testing tells you whether the controls are good enough. Singapore law requires a competent person to test the air where toxic dust is given off, at sufficient intervals, and to keep the results for at least 5 years. Personal samples taken in the breathing zone show what the worker actually breathes.

Health checks

Silica is one of the hazards that need statutory medical exams in Singapore. A designated workplace doctor does a pre-placement exam within 3 months of the worker starting. Periodic exams follow every 3 years. Give the doctor an up-to-date list of exposed workers.

Silicosis is a listed occupational disease. If a worker is diagnosed, the employer must report it to MOM through iReport within 10 days of being told. The doctor has a separate duty to report.

What the rules require (Singapore)

The Workplace Safety and Health (General Provisions) Regulations set the main duties for toxic dust.

  • Take all reasonably practicable steps to stop dust building up and to protect workers from breathing it (reg 39(1)).
  • Use, where appropriate, isolation of the work, enclosed systems, ventilation, local exhaust ventilation or wet methods (reg 39(2)).
  • Clean up toxic dust by washing, vacuuming or other means that do not make it airborne (reg 39(4)).
  • Air tested by a competent person at sufficient intervals; records kept for at least 5 years (reg 39(6), (8)).
  • No worker exposed above the permissible exposure levels in the First Schedule (reg 40). Respirable quartz: 0.1 mg/m3 over 8 hours. Cristobalite and tridymite: 0.05 mg/m3.
  • Pre-placement and 3-yearly medical exams by a designated workplace doctor for silica-exposed workers (MOM).
  • Silicosis is listed in the Second Schedule of the WSH Act. Diagnosed cases are reported to MOM within 10 days (MOM).
Short-term limit

Where no short-term limit is listed, the General Provisions Regulations treat a 15-minute average above 5 times the long-term limit as an exceedance (reg 40(2)). A few minutes of dry cutting can break it.

Common mistakes

  • Cutting dry because the water tank is empty or the hose is missing.
  • Using a shop vacuum or an extractor with a clogged filter.
  • Dry sweeping or blowing down with compressed air at the end of the shift.
  • Paper dust masks, no fit test, or masks worn under the chin.
  • Other trades working right beside the cutter with no screen.
  • No air monitoring, so nobody knows if the controls work.
  • Missing the 3-yearly medical exam for long-serving workers.
If you can see it, it is too much

The fine dust that harms the lungs is invisible. A visible cloud means far too much is in the air. Stop and fix the control.

In other countries

  • Indonesia: Permenaker No. 5 of 2018 on the working environment sets the threshold limit value (NAB) for respirable quartz at 0.025 mg/m3. That is a quarter of Singapore's limit.

Use it on site: the silica and construction dust checklist and the toolbox talk to brief your crew.

Sources

  1. Workplace Safety and Health (General Provisions) Regulations, Singapore Statutes Online (AGC).
  2. Requirements for medical monitoring, Ministry of Manpower.
  3. Workplace Safety and Health Act 2006 (Second Schedule, occupational diseases), Singapore Statutes Online (AGC).
  4. FAQs on occupational diseases under the WSHA and WICA, Ministry of Manpower.
  5. Construction dust (Construction Information Sheet No 36), UK Health and Safety Executive.
  6. Code of practice on safety and health in construction (revised 2022), International Labour Organization.
  7. Permenaker No. 5 Tahun 2018 tentang K3 Lingkungan Kerja, Kemnaker (Indonesia).

This is practical guidance, not legal advice. Laws and codes of practice change; always check the current official text and your site's own procedures.