In 2020, most states and territories lowered the workplace exposure standard (WES) for respirable crystalline silica from 0.1 mg/m3 to 0.05 mg/m3. This change was made after a health-based review of scientific evidence for silica dust showed that the WES should be reduced to prevent adverse health effects in workers, such as silicosis and lung cancer.
The WES review draft evaluation report for respirable crystalline silica recommended a lower WES of 0.02 mg/m3 to minimise the risk of lung cancer. Submissions to the public consultation for the WES review raised concerns that a WES of 0.02 mg/m3 would be difficult to measure and enforce.
Safe Work Australia investigated these concerns, as well as the option of a short term exposure limit (STEL) for respirable crystalline silica.
The report into measuring airborne concentrations of respirable crystalline silica found that there was uncertainty in measuring 0.02 mg/m3 with the current sampling and analysis equipment available in Australia. This was due to multiple reasons including sampling error, analytical uncertainty and laboratory reporting and performance. This report recommended that more work be done on measurement standards and laboratory techniques in Australia before the WES for respirable crystalline silica is reduced to 0.02 mg/m3. The full report is available at Measuring respirable crystalline silica.
The report into adding a STEL for respirable crystalline silica did not recommend a STEL if the 8 hour time weighted average WES is 0.05 mg/m3. The report stated that any exposure above 0.05 mg/m3, even for short periods of time, is not recommended and that a STEL would only provide additional protection when used in combination with a WES of 8 hour time weighted average of 0.02mg/m3. The full report is available at Short Term Exposure Limit for Respirable Crystalline Silica.
In 2021, we presented these reports to Safe Work Australia Members, which includes representatives from all Australian states and territories, plus representatives from workers and employers. After discussion, Members voted to keep the WES for respirable crystalline silica at 0.05 mg/m3 and to not to add a STEL.
Safe Work Australia continues to monitor developments in the measurement of airborne respirable crystalline silica to inform future reviews of the WES.