Silica - Occupational Health Hazards - MOSH
What is the hazard?
Silica is found in 60% of the rocks that make up the earth's surface. Certain types of sand are almost pure silica. The hazard exists when this material is released as a dust as a result of crushing and grinding. Breathing this free silica dust, either in large quantities or over a long period of time, may cause a lung disease called silicosis. The small dust particles remain in your lungs and scar tissue forms around them. This scarring, or fibrosis, stiffens the lungs and reduces their ability to exchange oxygen. The result is that you become short of breath, tire easily, and may begin to cough. These symptoms will become more severe the longer you work around and breathe the dust.
Who is affected?
The National Institute for Occupational Safety and Health (NIOSH) estimates that 1,200,000 workers are exposed to free silica in the following jobs:
- glass making
- enameling
- sandblasting
- tunneling
- chipping/buffing metals
- metallurgic processes
- stone and slate finishing
- foundry core making
- mining, quarrying and cutting of rock
- brick making
Individuals in the trades listed above are particularly at risk, but another three million workers in agriculture, chemical production and heavy construction may be exposed.
Medical Exams
Unless a doctor knows that you work around silica, the disease can go undiagnosed. Symptoms can come on gradually and resemble other problems, such as smoker’s cough or ordinary fatigue. Workers who are exposed to silica dust may want to consult a specialist in this area. Exposed workers should have an x-ray every two or three years and a lung function test once a year. Medical exams are helpful but cannot be relied upon as a primary protective measure. Preventive measures are essential because the disease is often well advanced before detection.
Prevention
The key to preventing silicosis is to control the exposure to free silica. Full employee cooperation is a must for effective prevention. MOSH requires that employers keep this exposure below established levels through engineering and administrative controls, such as:
- Substitution - Less toxic substances should be substituted for the free silica. For example:
- in sandblasting, use quartz-free grit or shot , or coal ash
- in foundry core making, substitute quarts-free grit
- in grinding operations, carborundum is a safe, effective substitute
- in pottery making, use alumina instead of flint
- Ventilation - Local exhaust systems should be used, with intake next to the heads of cutting and grinding tools.
- Wet Methods - Spraying with water in processes such as grinding or drilling may reduce the amount of dust by as much as 75%.
- Enclosure and Exhaust - A dusty operation can be enclosed and fitted with an exhaust hood, along with the necessary fans, vents, and air-cleaning devices.
Where engineering and administrative controls are not feasible, it may be necessary for a worker to wear a dust make or respirator. If a respirator must be worn, it is essential that the right type be used and that the respirator be fitted correctly. If a respirator program is required, workers should be examined medically to ensure that they would suffer no harmful effects from regular respirator use. MOSH can provide further information on respirators.
The Role of MOSH
The primary objective of the Maryland Occupational Safety and Health (MOSH) program is to assure, as far as possible, every Maryland worker a safe and healthful workplace. To protect workers from overexposure to silica, the Commissioner of Labor and Industry has adopted a permanent standard, which establishes limits based on the percent of free silica in the workplace atmosphere. Maryland’s standard is consistent with the Federal OSHA standard regarding silica exposure. MOSH will respond to worker complaints and will monitor work sites to measure the amount of silica in the air. Overexposure will result in citations requiring corrective action.