OSHA, NIOSH issue new hazard alert for crystalline silica exposure

OSHA and the National Institute for Occupational Safety and Health (NIOSH) recently issued a joint hazard alert about protecting workers from significant crystalline silica exposure during manufacturing, finishing, and installing natural and manufactured stone countertops.

The hazard alert follows reports of 46 workers in Spain and 25 workers in Israel who developed silicosis—an incurable, progressively disabling and sometimes fatal lung disease—as a result of exposure to crystalline silica in their work manufacturing stone countertops. Ten of the workers in Israel required lung transplants as a result of their condition.

OSHA and NIOSH have identified exposure to silica as a health hazard to workers involved in stone countertop operations in the United States, both in fabrication shops and during in-home finishing/installation. The alert jointly issued by OSHA and NIOSH explains how this hazard can be mitigated with simple and effective dust controls.

Crystalline silica is found in granite, sandstone, quartzite, various other rocks and sand. Workers who inhale very small crystalline silica particles are at risk for silicosis. Symptoms of silicosis can include shortness of breath, cough and fatigue, and may or may not be obviously attributable to silica. Workers exposed to airborne crystalline silica also are at increased risk for lung cancer, chronic obstructive pulmonary disease and kidney disease.

The hazard alert details what can be done at stone countertop fabrication and installation worksites to protect workers from exposure to silica. This includes monitoring the air to determine silica exposure levels; using engineering controls and safe work practices to control dust exposure; and providing workers with respiratory protection when needed, training, and information about the hazards of silica.

OSHA’s current permissible exposure limit (PEL) for crystalline silica is 100 micrograms per cubic meter of air as an 8-hour time-weighted average (TWA). However, in August 2013, the agency proposed to reduce the exposure limit to an 8-hour TWA of 50 micrograms per cubic meter and create a comprehensive standard for silica exposure including medical surveillance, worker training, and recordkeeping measures. Public hearings on the proposal took place from March 18–April 4, 2014.

The following are some of the engineering and work practice controls to reduce silica exposure recommended in the hazard alert:

• Use water spraying systems and remote-controlled tools at the impact site where a saw or grinder generates dust.
• Use hand tools (e.g., drills, masonry saws, grinders) equipped with a shroud and a vacuum with a high efficiency particulate air (HEPA) filter when methods are not practical.
• Use wet sweeping or HEPA-filtered vacuuming instead of dry sweeping or compressed air.
• Pre-wash stone slabs prior to cutting.
• Implement regular and thorough housekeeping procedures for water slurry and settled dust.