![]() It is consistent with the international recommended exposure limit of 0.05 mg/m 3 as a time-weighted average for up to 10 h per day during a 40-h week ( 1). The Australian standard for workplace exposure to silica is 0.05mg/m 3 (50 μg/m 3) over an 8-h working day, for a 5-day working week ( 5). According to a study by Steenland ( 3), RCS can remain in the lungs even if the exposure is stopped and may continue to adversely affect its functions. When inhaled, RCS can penetrate deep into the lungs and cause irreversible lung damage including chronic bronchitis, chronic obstructive pulmonary disease (COPD), emphysema, silicosis, and silico-tuberculosis ( 3, 4). Silica dust particles with size from 0.01 to 100 μm in diameter are a significant health concern ( 2). During mechanical processes such as crushing, cutting, drilling, or grinding of natural stone, or man-made products that contain silica, workers generate silica dust commonly referred to as respirable crystalline silica (RCS) ( 1). More stringent prevention strategies are therefore recommended to protect mine workers from RCS exposures.Ĭrystalline silica is one of the most abundant minerals found in the earth's crust and it is used in many products across a variety of industries and occupations including underground mining. Miners are susceptible to adverse respiratory health effects at low levels of RCS exposure. ![]() Miners exposed to RCS had a significantly higher prevalence of phlegm ( p = 0.017) and any respiratory symptom ( p = 0.013), even at concentrations within the exposure limit. The estimated exposure levels of RCS (geometric mean 0.008mg/m 3, GSD 4.151) declined over the study period ( p < 0.001) and were below the exposure standard of 0.05 mg/m 3. Logistic regression analyses were performed to ascertain the association between RCS concentrations and the prevalence of respiratory symptoms among mine workers. A standardized respiratory questionnaire was also administered to collect information related to their respiratory health. This study used a large population database of 6,563 mine workers from Western Australia who were examined for personal exposure to RCS between 20. Occupational exposure to respirable crystalline silica (RCS) is common in a range of industries, including mining, and has been associated with adverse health effects such as silicosis, lung cancer, and non-malignant respiratory diseases. 2Department of Epidemiology and Prevention, Center for Clinical Sciences, National Center for Global Health and Medicine, Tokyo, Japan.1School of Population Health, Curtin University, Perth, WA, Australia.Krassi Rumchev 1 *, Dong Van Hoang 2 and Andy Lee 1
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