Fine silica dust is common on UK sites where stone, concrete or brick is cut, drilled or ground. Many employers still treat it as a nuisance rather than a serious health risk. This article summarises what respirable crystalline silica (RCS) is, the harm it can cause, and what the law expects you to do.
What is respirable crystalline silica?
Crystalline silica occurs naturally in sand, sandstone, granite, clay and many building materials. Cutting, drilling, grinding or crushing releases very fine particles that can reach deep into the lungs. That respirable fraction is RCS. Quartz is the usual form in concrete, mortar, brick and engineered stone. Any dusty task involving these materials can expose workers above safe limits if controls are weak.
Industries and tasks most at risk
Construction has the largest exposed workforce in the UK, but risk is not limited to building sites. High-exposure tasks include cutting or polishing stone or concrete, tunnelling in silica-bearing rock, dry sweeping or blow-down of dusty areas, sand or abrasive blasting, ceramic and glass work, and fabrication of engineered stone worktops. Manufacturing, quarrying, mining and some dental laboratories can also be affected.
Health effects of silica exposure
Long-term inhalation of RCS can cause silicosis, an irreversible scarring of the lung tissue. Early disease may have no symptoms, which is why surveillance matters. Later, workers may develop breathlessness, cough and reduced stamina. RCS is also associated with chronic obstructive pulmonary disease (COPD), lung cancer and kidney disease. Quartz and cristobalite in respirable form are classified as human carcinogens (IARC Group 1).
UK legal duties under COSHH
Under the Control of Substances Hazardous to Health Regulations 2002 (COSHH), you must assess RCS exposure and control it. The workplace exposure limit (WEL) for RCS is 0.1 mg/m³ as an eight-hour time-weighted average. Prevent exposure where reasonably practicable; otherwise reduce exposure to as low as reasonably practicable and in any case below the WEL. Typical controls include water suppression, on-tool extraction, enclosed processes, suitable RPE, and vacuum cleaning instead of dry sweeping.
Health surveillance requirements
Where exposure remains despite controls, COSHH regulation 11 requires suitable health surveillance. For RCS this usually means a baseline health questionnaire and spirometry before or soon after starting exposed work, then periodic reviews (often every one to three years, depending on risk). The aim is to spot lung effects early. Assessments should be done by a competent occupational health provider, with confidential records kept for at least forty years.
Practical steps for employers
Review every task that could create silica dust in your COSHH assessments. Check existing controls against the WEL. Use water and extraction on cutting and grinding work; train staff on RPE face-fit and maintenance. Set up surveillance before new starters enter exposed roles, and keep risk assessments and health records current. HSE inspects silica controls actively, and enforcement, including prosecution, is used where standards are poor.
