A recent study in the Annals of Work Exposures and Health examined the effectiveness of OSHA’s engineering controls for silica dust.
Silica is a common mineral found in concrete, glass, mortar, brick, stone, and sand. Manufacturing, cutting, sanding, or drilling these materials can produce respirable crystalline silica, which is 100 times smaller than a grain of sand.
OSHA estimates that 2.3 million workers in the U.S. are routinely exposed to respirable silica. Inhaling this dust leads to an increased risk of several diseases. Among these are silicosis, lung cancer, kidney disease, and chronic obstructive pulmonary disorder, or COPD.
OSHA published two standards on respirable silica, designed to protect workers. In the construction standard, for example, OSHA suggested systems that deliver water to the cutting surface, shrouds, dust collection systems, and HEPA filtration. By implementing these controls, it is assumed that the levels of respirable silica will remain below the personal exposure limit, or PEL.
The study, mentioned above, challenges that assumption. Researchers took air samples from a construction site. They also took personal air samples from 19 workers at the same site over 13 days. The workers performed such tasks as core drilling, cutting with a walk-behind saw, grinding, and jackhammering. Researchers noted whether or not the workers were implementing the OSHA controls. Some did not.
The researchers found that over half the workers were exposed to respirable crystalline silica above the OSHA Action Level. And nearly one third of the exposures were above the PEL. One of the work site samples exceeded the PEL. The study suggests that OSHA's engineering controls for silica dust may not prevent hazardous levels of the dust. Workers performing certain tasks, along with the rest of the work site, face levels of silica dust above the PEL. In turn, they are at greater risk of developing one of the diseases associated with breathing silica dust.
