Silica dust carried in the air or in water mist generated from water suppression can be further controlled through isolation controls such as guards , enclosures and barriers . In addition to those controls , administrative controls and respiratory protective equipment ( RPE ) should also be used . These controls include :
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− − − using guards , plastic flaps or brush guards around the rotating blade , tool or equipment to enclose the water spray providing distance between the work process and the worker o for example , operator positioning when using bridge saws or routers providing distance between workers using powered hand tools and other workers in the workplace , and providing physical barriers between different workers and workstations to prevent the water mist moving into other work areas or towards other workers , including office workers .
Routine maintenance and cleaning will help to ensure guards continue to work effectively .
LEV is designed to remove airborne contaminants from the air before they reach the breathing zone of workers . It is the most effective control for large quantities of silica dust when it is applied close to the source of generation .
For drills , routers , saws and other equipment , an appropriately designed LEV should be fitted . The manufacturer of on-tool extraction and LEV equipment can provide information about how the equipment captures dust to determine its suitability for a particular workplace .
A simple LEV system most commonly comprises of :
− an extraction hood to capture and remove contaminated air near the point of release − ducting to connect to an air-cleaning system − a fan to move the air through the system , and − an exhaust stack outside the building to disperse the cleaned air .
While these controls may reduce background levels of silica dust , they are not as effective in reducing exposure to silica dust for workers performing high exposure tasks . High exposure tasks should be performed using on-tool controls that suppress or capture dust at the source , such as integrated water suppression or dust extraction .
If there is too much distance between an extraction unit and the dust generation point , the capture strength or velocity of extraction at the point of dust generation is too low to adequately capture the silica dust generated .
For extraction to be effective , the cutting point needs to be close to the extraction hood . The nature of the work may not allow this , or it may require the worker to constantly reposition the work piece or hood . For example , a stonemason cutting a sink hole into a stone benchtop is regularly moving and turning the tool , which generates dust in a range of directions and angles .
Managing the risks of respirable crystalline silica from engineered stone in the workplace - Code of Practice 34 of 57