Respirable crystalline silica (RCS) is found in stone, rocks, sands and clays. Exposure to RCS over a long period can cause fibrosis (hardening or scarring) of the lung tissue with a consequent loss of lung function.
Silicosis results in a loss of lung function and severe shortness of breath, it can even be fatal. Silicosis can also increase your risk of getting other serious and potentially life-threatening conditions.
Sufferers are likely to have severe shortness of breath and may find it difficult or impossible to walk even short distances or up stairs. The effect continues to develop after exposure has stopped and is irreversible. Sufferers usually become house- or bed-bound and often die prematurely due to heart failure.
Acute silicosis is a rare complication of short-term exposure to very large amounts of silica. This condition is life-threatening and associated with very significant clinical consequences.
Silica may also be linked to lung cancer. Precautions taken to control the risk of fibrosis will serve to control the risk of lung cancer. Workers with silicosis are at an increased risk of tuberculosis, kidney disease and arthritis.
Chronic obstructive pulmonary disease (COPD)
Exposure to RCS may also cause chronic obstructive pulmonary disease (COPD). The symptoms are chronic cough, sputum production and breathlessness. The condition is slow to develop and is rarely seen in people under 40. It can be very disabling and is a leading cause of death. Severe unremitting asthma is classed as a COPD.
You can find more information on how to protect workers from COPD.
Exposure to RCS
Occupations with exposure to RCS include:
- quarrying
- slate works
- foundries
- potteries
- stonemasonry
- construction (when cutting or breaking stone, concrete or brick)
- industries using silica flour to manufacture goods
Amounts of silica in different types of stone
| Type of stone | Percentage of silica |
|---|---|
| sandstone, gritstone, quartzite | more than 70% |
| concrete, mortar | 25% to 70% |
| shale | 40% to 60% |
| china stone | up to 50% |
| slate | up to 40% |
| brick | up to 30% |
| granite | up to 30% |
| ironstone | up to 15% |
| basalt, dolerite | up to 5% |
| limestone, chalk, marble | up to 2% (but these can contain silica layers) |
RCS particles are produced during many work tasks, including sandblasting, mining, rock drilling, quarrying, brick cutting, glass manufacturing, tunnelling, foundry work, stoneworking, ceramic manufacturing and construction activities.
Controlling the risks of RCS
In Britain, RCS exposure has a workplace exposure limit (WEL), which contains exposure below a set limit, preventing excessive exposure. The WEL for RCS is 0.1 mg/m3 expressed as an 8-hour time-weighted average (TWA). Exposure to RCS is also subject to the Control of Substances Hazardous to Health Regulations 2002 (COSHH).
Health surveillance must be provided to workers who are regularly exposed to RCS dust and there is a reasonable likelihood that silicosis may develop.
You should consider health surveillance for silicosis for workers who are involved in high-risk occupations, including construction, foundry work, brick and tile work, ceramics, slate, manufacturing, quarries and stonework.
Find out more
Guidance for workers is available on control of exposure to silica dust.
There is also detailed guidance in the COSHH essentials sheets.
For occupational health professionals, there is separate guidance on health surveillance for those exposed to respirable crystalline silica (RCS).
There is general information about silicosis on the NHS website.