The principal airborne hazards in the mining industry include several types of particulates, naturally occurring gases, engine exhaust and some chemical vapours.
The principal physical hazards are noise, segmental vibration, heat, changes in barometric pressure and ionizing radiation.
These occur in varying combinations depending on the mine or quarry, its depth, the composition of the ore and surrounding rock, and the method(s) of mining.
Among some groups of miners who live together in isolated locations, there is also risk of transmitting some infectious diseases such as tuberculosis and hepatitis (B and E).
Miners’ exposure varies with the job, its proximity to the source of hazards and the effectiveness of hazard control methods.
Airborne particulate hazards
Free crystalline silica is the most abundant compound in the earth’s crust and, consequently, is the most common airborne dust that miners and quarry-workers face.
Free silica is silicon dioxide that is not chemically bonded with any other compound as a silicate.
The most common form of silica is quartz although it can also appear as trydimite or christobalite.
Respirable particles are formed whenever silica-bearing rock is drilled, blasted, crushed or otherwise pulverised into fine particles.
The amount of silica in different species of rock varies but is not a reliable indicator of how much respirable silica dust may be found in an air sample.
Exposure can occur in any mining operation, surface or underground, where silica is found in the overburden of a surface mine or the ceiling, floor or ore deposit of an underground mine.
Silica can be dispersed by the wind, by vehicular traffic or by earth-moving machinery.
With sufficient exposure, silica can cause silicosis, a typical pneumoconiosis that develops insidiously after years of exposure.
Exceptionally high exposure can cause acute or accelerated silicosis within months with significant impairment or death occurring within a few years.
Exposure to silica is also associated with an increased risk of tuberculosis, lung cancer and of some autoimmune diseases, including scleroderma, systemic lupus erythematosus and rheumatoid arthritis.
Freshly fractured silica dust appears to be more reactive and more hazardous than old or stale dust.
This may be a consequence of a relatively higher surface charge on freshly formed particles.
The most common processes that produce respirable silica dust in mining and quarrying are drilling, blasting and cutting silica-containing rock.
The hand-held jack-hammer or sinker drill operates on the same principle but on a smaller scale.
This device conveys a significant amount of vibration to the operator and with it, the risk of vibration white finger.
Vibration white finger has been found among miners.
Respirable coal mine dust
Respirable coal mine dust is a hazard in underground and surface coal mines and in coal-processing facilities.
It is a mixed dust, consisting mostly of coal, but can also include silica, clay, limestone and other mineral dusts.
Coal mine dust
Coal mine dust causes coal workers’ pneumoconiosis (CWP) and contributes to the occurrence of chronic airways disease such as chronic bronchitis and emphysema.
Coal of high rank (e.g., high carbon content such as anthracite) is associated with a higher risk of CWP. There are some rheumatoid-like reactions to coal mine dust as well.
Asbestos
Asbestos exposure occurs among asbestos miners and in other mines where asbestos is found in the ore.
Among miners throughout the world, exposure to asbestos has elevated the risk of lung cancer and mesothelioma. It has also elevated the risk of asbestosis (another pneumoconiosis) and of airways disease. — www.iloencyclopaedia.org
