Silica dust has long posed a hazard in industries using brick, natural stone and concrete products. However, the growing use of engineered stone in kitchen and bathroom countertops is now increasing risk to workers in other applications.

Engineered stone can contain substantially higher amounts of silica than natural stone – over 90% compared with less than 45% in granite. Manufacturing, finishing and installing engineered stone can therefore generate high levels of dangerous silica dust and put workers at risk of developing debilitating and potentially fatal lung conditions.

What is silica?

Silica is a mineral found in stone and other construction materials. Materials that contain crystalline silica include:

- Soil
- Sand
- Concrete
- Mortar
- Granite and other minerals
- Engineered stone

Breaking up these materials releases dust. Silica dust is generated during common construction tasks such as cutting, drilling, grinding and polishing stone materials. The dust is made up of small particles that can become airborne and cause a respiratory hazard.

Respirable crystalline silica (RCS) is a term for the fine dust created that gets deep into the lungs when inhaled. This dust is too fine to see with regular lighting and inhaling just a small amount can do a lot of damage.

In the UK and EU, the Workplace Exposure Limit (WEL) for silica dust is just 0.1mg/m3 over 8 hours.

This image illustrates 0.1mg/m3 of silica dust, shown above the penny coin. Law in the UK and EU requires companies to ensure exposure is well below the amount shown here.

Limits are lower in the USA and Australia. North America’s Permissible Exposure Limit (PEL) is set at 50µg/m3 and Australia’s WEL at 0.05mg/m3, halving silica exposure over an 8-hour working day.

No limit should be considered ‘safe’ as inhaling any amount of silica dust is harmful, and exposure should be reduced as far as possible.

Health effects

Silica dust can cause inflammation when particles enter the lung and, over time, lead to areas of hardened and scarred tissue (fibrosis).

Silicosis is an incurable lung disease caused by inhaling silica dust, usually over a period of many years. The condition is progressive and can lead to disability and death.Inhaling silica dust can also cause lung cancer, kidney disease and autoimmune disease.

Protecting employees

Implementing an effective respiratory protective equipment (RPE) programme is key to protecting employees against dangerous silica dust. A risk assessment is required to identify hazards and measure concentration levels in the workplace. Control measures can then be put in place.

RPE may be one of several controls – ideally the last line of defence after substitution, extraction and other engineering controls. Using alternative or pre-cut materials can eliminate the silica hazard altogether. On-tool extraction and local exhaust ventilation systems reduce the amount of dust in the air. Water suppression can also be used to reduce airborne concentration levels.

Using RPE to further reduce exposure, a respirator with a high-efficiency particulate filter offering a UK APF of at least 20 should be selected. This includes FFP3 disposable respirators, as well as reusable half or full face masks fitted with P3 filters.

Tight-fitting RPE, including disposable respirators, half and full face masks, must be fit tested to ensure protection. Each wearer must be tested to make sure their specific model and size of mask is able to properly seal with the face. Wearers of tight-fitting RPE must also be clean-shaven in the area of the face seal. Find out more about respiratory protection and facial hair.

Loose-fitting respirators are protective devices that do not rely on a seal to protect the worker. Bearded workers who are exposed to silica dust must consider a loose-fitting PAPR to be sufficiently protected. Such products would typically be certified to EN 12941 and have a TH2PSL or TH3PSL performance rating. Learn more about loose-fitting respirators.

Exposure to silica dust must be controlled to protect against incurable, potentially fatal lung conditions. Assessing the risks and implementing appropriate measures to reduce airborne dust is key to protecting employees from inhaling dangerous levels of silica. Respirators should be selected carefully to ensure adequate protection against the hazard as well as suitability for the task and wearer.

Find more information on respiratory protection.
Learn about different forms of respiratory hazards encountered in the workplace.