Page 54 - OHS, October 2023

RESPIRATORY Monitoring Exposure of and Protecting Employees from Silica Dust Understanding the challenge posed by silica dust exposure on site and in confined spaces, and the comprehensive standards and measures used to combat its peril. BY TIM TURNEY Approximately 2.3 million workers in the United States exposure, equal to an eight-hour time-weighted average. For ref- erence, the PEL of any hazardous dust in the workplace is ten are exposed to Respirable Crystalline Silica (RCS) or milligrams per cubic meter. silica dust every year, which is now known to possess a similar magnitude of risk as the more widely under- As with any known workplace health risk, the most effec- tive means of reducing worker exposure to respirable crystalline stood asbestos dust. Crystalline silica is found in many commonly silica is a correctly implemented scheme of controls using the hi- used construction materials, including sand, gravel, clay, stones, concrete, bricks and quartz. When these materials are broken, erarchy of controls. This can help reduce both the likelihood of workers developing health complications such as silicosis and the stirred or otherwise disturbed through cutting, drilling, grinding potential legal ramifications for employers. Measures include a or crushing, minuscule dust particles are created. When inhaled, these particles travel deep into the lungs and can cause incurable correctly executed program of air monitoring, which can include both monitoring at the site level and on an individual employee and sometimes deadly respiratory diseases such as silicosis, chron- level using personal sampling pumps. Air monitoring can quan- ic obstructive pulmonary disease and kidney disease. The Department of Labor has recently (June 2023) proposed tify exposure levels, or if controls are in place, check that they are effective and measure any residual risk. These pumps are essential a new ruling to limit silica dust exposure by its Mine Safety and in places where there is a significant risk of highly concentrated Health Administration (MHSA) to better protect miners’ health. This comes almost exactly ten years after The Occupational Safe- hazardous pollutants in the surrounding air, for example, con- fined spaces and sites that emit large quantities of fumes. ty and Health Administration (OSHA) proposed a rule aimed at curbing workers’ exposure to crystalline silica across all indus- tries by updating the Permissible Exposure Limit (PEL) to be in Control Measures line with modern understanding of the hazard. The newest pro- In controlling dust, the usual risk control hierarchy applies. Where posal by the MHSA would see the PEL of silica dust at or below the risk cannot be eliminated entirely, a safer form of the product 50μg/m3 (micrograms per cubic meter of air) for a full shift of should be used. If this is not feasible, the process should be changed 54 Occupational Health & Safety | OCTOBER 2023 www.ohsonline.com M G White/Shutterstock.com