Preventing Silicosis and Deaths among Rock Drillers
| NIOSH Issues Alerts in response to immediate occupational health hazards. The Alerts are designed to Inform workers that they are at risk and to propose ways of reducing that risk. Hazardous conditions cannot be prevented unless workers are in fact aware of hazards and how to avoid them. To accomplish this task, NIOSH alerts request the assistance of health and safety officials, editors of the appropriate trade journals, and employees in the effort to inform workers and implement recommendations. The goal of the Institute is to prevent occupational injury and disease through dissemination of these warnings. |
Who is at Risk?
Workers who drill into rock containing silica or remove silica-containing debris after drilling are at most risk for developing silicosis. Silica is the most abundant mineral on the earth's surface; consequently, there is a high probability of exposure. Silicosis has been diagnosed in rock drillers employed in caisson construction, metal mining, slate and rock quarries, tunnel construction, and highway and dam construction.
How Does Exposure Occur?
The drilling process can create large quantities of silica dust. During drilling, the silica present in the rock is fractured into very fine particles which can then be inhaled by the worker. The smallest particles, once inhaled, deposit deep in the lungs, where they can cause severe damage.
What are the Health Effects?
Once silica particles enter the lungs and become trapped, the lung tissue scars and forms nodules. As the condition worsens, the nodules become progressively larger. The nodules make breathing increasingly difficult, and eventually the worker may die of respiratory failure.
The symptoms of silicosis include shortness of breath, cough, and difficulty in breathing with physical exertion. Because of the common nature of these symptoms, the disease is frequently misdiagnosed or proceeds undetected. The disease is diagnosed on the basis of its symptoms in conjunction with work history and X-ray assessments of dust-induced lung damage.
How Can Workers Be Protected?
NIOSH recommends the following measures to reduce crystalline silica exposures in the workplace and prevent silicosis and silicosis-related deaths:
- Before rock drilling begins, assess the potential for worker exposure to crystalline silica.
- Use control measures such as wet drilling and exhaust ventilation to minimize exposures,
- Conduct air monitoring to measure worker exposures.
- Provide workers with training that includes information about health effects, work practices, and protective equipment for crystalline silica.
- Practice good personal hygiene to avoid unnecessary exposure to silica dust.
- Wear washable or disposable protective clothes at the worksite. Shower and change into clean clothes before leaving the worksite to prevent contamination of cars, homes, and other work areas.
- Use respiratory protection when source controls cannot keep silica exposures below the NIOSH recommended exposure limit (REL).
- Provide periodic medical examinations for all workers who may be exposed to crystalline silica,
- Post signs to warn workers about the hazard and to inform them about required protective equipment.
- Report all cases of silicosis to State health departments and to OSHA or MSHA.
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