Socotec Advises on Silica Dust Inhalation

NEW GUIDANCE relating to respirable crystalline silica (RCS), a by-product of slate and tile cutting, has been issued by inspection, testing and compliance company Socotec.

When working with slate and tiles, certain construction activities are known to produce high levels of crystalline silica dust which, if not monitored and controlled, can lead to chronic respiratory conditions.

With an estimated 600,000 workers in the UK exposed to silica dust each year, and an average of 600 silica-related deaths per annum, it is important that organisations understand the health risks that come with slate and tile cutting and how best to protect their workers against the harmful effects of silica.

Where is RCS found?

Silica is a natural substance found in many types of stone, sand and clay – including bricks, concrete, slate and tiles – and occurs in both crystalline (including quartz, cristobalite and tridymite) and non-crystalline (or amorphous) forms.

The crystalline silica content within each material varies, with tiles containing 30-45%, slate 20-40%, brick up to 30% and concrete 25-70%. RCS can be created when these materials undergo cutting, mining, blasting, drilling and polishing.

High levels of crystalline silica dust are released when saws are used to cut roof slate and tiles, regardless of the size of the material or the length of time that it is cut for. There is a considerable risk to workers who inhale excessive quantities of RCS over an extended period, such as when when packing and stacking slates after they have been split and dressed.

What can be done to limit exposure?

Ways to limit exposure include:

  • Using engineering controls such as enclosures, hoods and other types of Local Exhaust Ventilation (LEV)
  • Applying wet methods of cutting, chipping, drilling, sawing and grinding to eliminate or minimise dust creation
  • Using a handheld cut-off saw with a water suppression attachment connected to a pressurised water container
  • Douse equipment with water during the clean-up process and debris removal
  • Avoiding high pressure spraying, brushing and sweeping that could disturb silica dust
  • Where engineering controls are not reasonably practicable, wearing, storing and maintaining the correct Respiratory Protective Equipment (RPE) – an FFP3 disposable dust mask or half mask with P3 filters, all of which must be face-fit tested
  • Replacing seals and worn cutting discs when necessary
  • Employing dust extraction equipment in dedicated workspaces
  • Using covered chutes and skips/screening off areas to prevent the spread of dust
  • Creating space for a dedicated, well-ventilated cutting area (control rooms, barriers and enclosures) and limiting the number of people who can access the workspace

Substituting silica-containing materials with a lower RCS content or eliminating silica-based substances completely is also an effective option to reduce the level of exposure, although this is not always viable.

Specifying half or bespoke sized tile sizes from manufacturers at the building design stage may also reduce the need for cutting.

What should you do?

According to Socotec, only a small amount of crystalline silica dust is required for workers to contract respiratory conditions, which is why the the Health and Safety Executive requires employers to monitor dust levels and ensure that exposures remain as low as reasonable practicable (ALARP) while also being below the current Workplace Exposure Level of 0.1 mg/m3 over an eight-hour time weighted average (TWA).

Employers are required to regularly monitor exposure levels in order to ensure that any control measures such as LEV or even RPE are working effectively.

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