Publication Details

Alamango, K., Whitelaw, J. & Apthorpe, L. (2015). Have you got your head in the sand? Respirable crystalline exposures of restorative stonemasons. 2015 AIOH Conference Proceedings (pp. 10-16). Victoria: Australian Institute of Occupational Hygienists Inc.


Restoration stonemasons play a vital role in preserving culturally significant heritage buildings and the majority of culturally significant buildings in Sydney are constructed using Sydney sandstone, with an average silica content of 75%. Stonemasons conducting the close inspection required for precision sandstone grinding restoration works are considered at significant risk of exposure to respirable crystalline silica (RCS). An occupational hygiene survey was conducted to assess the risk of RCS exposure of restoration stonemasons conducting various tasks. Exposure monitoring for respirable dust (RD) and RCS was undertaken and the task of grinding sandstone determined as the highest exposure risk. 'Spinning' and 'Chopping out' tasks were identified as 'high risk' activities with excessive exposures of 4, 6 and 12 mg/m3, well above the workplace exposure standard (WES) of 0.1 mg/m3. Short duration task monitoring was conducted to better evaluate worker exposures and job rotation during the highest risk grinding task was not determined as a suitable control to reduce stonemason exposures. A trial was undertaken using on-tool dust collecting shrouds attached to local exhaust ventilation (LEV) system to evaluate the effectiveness and suitability to grinding tasks, with a 99% exposure reduction achieved. Reducing stonemason exposures below the WES was still not possible for grinding tasks; and numerous control measures were recommended to ensure workers are not exposed to concentrations of RCS likely to cause risk to health. Implementation of a combination of control measures is essential in reducing RCS exposure risk. Controls selected in line with the hierarchy of controls include:- mini enclosures, wet methods of dust suppression, on-tool dust collection shrouds and local exhaust ventilation (LEV); along with appropriate respiratory protection commensurate to exposure and powered air purifying respirators (PAPR) when grinding sandstone. Stonemasons grinding sandstone are considered at high risk of RCS exposure. They were encouraged to participate in equipment trials and evaluate their effectiveness. The more informed the stonemasons became, the more inspired they were to reduce their RCS exposure and integrate small, effective changes during sandstone restoration activities. Utilising knowledge from industry experts was invaluable in ensuring a successful trial, and gaining the confidence of the cohort. Throughout the risk assessment process, the stonemasons increased their knowledge and understanding of RCS.