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Occupational exposure limits are the maximum allowable concentrations of hazardous elements in the air. They are defined by scientific laboratories in order to control the level of pollution in different areas. Among the main atmosphere pollutants are large-scale industry, domestic boilers and transport. The portion of each of these pollutants is different from place to place, but industrial companies are considered to be the worst pollutants. The major sources of artificial aerosol pollution of the atmosphere are thermal power plants that burn a large amount of coal with high ash content, concentrating mills, metallurgical, cement, magnesite and soot plants. |
Waste dumping as a source of pollution
Many countries having outlet to the sea bury such substances and materials as ground extracted during channel dredging, drilling slag, industrial waste products, construction waste, solid waste, explosive and chemical compounds, radioactive waste. The extent of such burial reached about 10% of the whole mass of polluting materials that enter the world oceans. The reason for waste dumping into the sea is the possibility of the marine environment to process large quantities of organic and inorganic matters without doing particular harm to the water. But this capability is not endless. That's why dumping is seen as a forced measure, a temporary necessity caused by the imperfection of the existing technologies. The residues of industrial production contain various organic substances and compounds of heavy metals. During dumping of wastes into the water a part of the polluting materials remain in the upper layers of water and dissolve there changing the qualitative characteristic of the water. Another part of the wastes turns into bottom sediment. Suspended materials concentration in the water increases. The presence of organic waters often leads to fast consumption of oxygen and very often to its disappearance, dissolution of suspensions, accumulation of metals.
Presence of a large amount of organic substances creates steady reducing environment in which a special kind of silt waters is created containing hydrogen sulfide, ammonia, and ions of metal. In case of presence of synthetic surface-active substances the gaseous exchange between the water and the air is broken.
