4. Common Sources of Exposure
Common Sources of Exposure Presentation
Key Points
RCS is found in a very wide range of work environments from naturally occurring sources to materials used in processes. The type of industries where it is present vary widely from agriculture to oil and gas extraction, from mining and quarrying to manufacturing, from construction to water a sewage treatment, and from ceramics and pottery to jewellery manufacture. The work environments can vary from outdoor workplaces such as farming to indoor environments such as metal foundries. Those affected may be single tradesmen to large industrial workforces. Some examples of work environments are given below.
Agriculture - In agriculture cultivation of arable land can cause significant exposure to RCS dust. The level of exposure will depend upon the concentration of crystalline silica in the soil type, the moisture content of the soil and the method of cultivation. Mechanical cultivation methods will generate significantly higher levels of dust than manual methods, especially when the soil has low moisture content. Tractor operators are shown to have much lower exposure if their tractor has an enclosed cab and the cab door is kept shut when cultivating.
Construction - Crystalline silica is present in many of the materials used in construction. These include concrete, mortar, bricks, tiles, stone and fibre cement products. The construction operations that generate significant amounts of RCS include cutting, drilling, grinding and polishing of materials containing crystalline silica. Other areas include the sand blasting of structures and items using silica sand and demolition of structures made of materials containing crystalline silica.
Mining and Quarrying - Mining and quarrying operations where rock containing crystalline silica is drilled, blasted, crushed, screened and cut generates high concentrations of RCS dust. If workers in these industries are not adequately protected from exposure to the dust they will be at high risk of contracting silicosis or a related disease.
Metal Foundries - Quartz sand is commonly used to form the moulds and cores used in metal casting foundries. High levels of RCS exposure can occur during mould formation, mould knock-out and fettling processes in these workplaces.
Oil and Gas Production - Oil and gas production often involves the use of quartz sand to prop open the cracks in the oil and gas containing rocks to increase flowrate. The handling of this sand during the well formation process can be a source of RCS exposure.
Stone Work - Stone masons involved in carving decorative building stonework, restoration of existing decorative stonework and carving stone sculptures can be at high risk of exposure to RCS. This work often involves the stone worker being close to the source of the dust. When mechanical tools are used for cutting, carving and polishing level of dust generated can be significantly higher than with manual operations.
Pottery and Ceramics - Workers in potteries that do not adequate level of dust control have been shown to have high levels of silicosis. RCS exposure in these industries can occur from handling the powdered raw materials and from dried clay and slip on surfaces and clothing.
Brick Making - Brick making is another industry where high level of RCS dust exposure is possible. Clay bricks can contain up to 40% crystalline silica. Exposure can occur during the milling, screening and transport of the raw materials as well as during brick facing and removal of brick from the kiln.
Other Industries - Many small artisan industries, such as jade polishing, can also be work environments where significant RCS exposure can occur. Where this work is being carried out in the home environment family members as well as the workers may be at risk of contracting a RCS related disease.