Respiratory Crystalline Silica (RCS)  is hazardous to health, exposure can lead to respiratory diseases: Occupational Asthma, Chronic Obstructive Pulmonary Disease (COPD), and Silicosis.

The current WEL Workplace Exposure Limit for RCS is 0.1mg.m^-3 as an 8 hour TWA (time weighted average). At exposures of as little as 0.3 mg.m^-3 there is a 20% risk of developing silicosis.

A further reduction of the WEL to 0.05 mg.m^-3 may be introduced.

Silicosis – A slow, progressive, irreversible disease that usually develops many years after initial exposure. The main symptom is breathlessness. In severe cases death can ensue. Silicosis is diagnosed by chest X‑ray where the presence of rounded nodules of scar tissue on the lungs is visible as white opacities. The highest risk of developing silicosis is from exposure to dry, freshly fractured fine particles of RCS that are generated during many common workplace tasks such as drilling, cutting, grinding, polishing etc.

Acute Silicosis – People who experience exceptionally high exposures over a few months or years can develop this rapidly progressive and often fatal condition (exposures in the order of 1.5 mg.m^-3 on a daily basis for a year or two). This can result in death within months of exposure.

Lung cancer – Heavy and prolonged exposure to RCS under the conditions that produce silicosis can cause lung cancer.

Chronic Obstructive Pulmonary Disease (COPD) – an umbrella term that covers emphysema and chronic bronchitis. It is characterised by impaired airflow within the lungs and is not fully reversible. The symptoms are cough with phlegm, and/or wheezing and breathing difficulties and it too can result in death.

Workers with silicosis are at increased risk of tuberculosis and may develop kidney disease and arthritis (and related conditions).

Smoking may influence the development of symptoms in silica-exposed workers.

FACTORS AFFECTING EXPOSURE TO RCS

Type of stone	The higher the RCS content of the stone, the more hazardous the material.
Nature of task/activity	Different tasks generate vastly differing levels of dust. Simple dimensioning of stone with a circular saw generates comparatively little dust as water suppression is usually provided. Decorative work (dressing and finishing) usually liberates substantial quantities of dust as power tools are used and water suppression is difficult.
Wet or dry working	Pre-soaking stone reduces dust levels considerably. Water suppression should be provided wherever practicable.
Hand or power tools used	Power tools generate considerably more dust than hand tools. The type of tool used and the speed of the tool are important factors.
Provision of Local Exhaust Ventilation	Exhaust ventilation booth enclosure provided where practicable; the operator must be working within the effective capture zone of the booth. If instead of a booth Capture Hoods are provided they have to be positioned and used correctly. Capture Hoods are likely to be much less effective than a Booth Enclosure. Routine daily/weekly checks should be in place Maintenance regime should be in place.
Length of time on the task	Intermittent or prolonged.
Segregation of the work areas	High dust generating activities should be in a segregated work area where possible.
Provision and maintenance of RPE	Correct RPE used, Face fit tests done RPE stored and maintained properly.
Work Practices	Vacuum off stone debris rather than blowing it off. Vacuum rather than sweep up.