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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. |
Chemical pollution of natural waters
All of us have seen television ads and cartoons showing us evil corporations putting their pipes with hazardous chemicals flowing right into water reservoirs. Let's try to find out if that's really that way and if it is, what is done to change the existing way of things.
Each water reservoir is integrally connected with its surroundings and with its environment. It is influenced both by water and underground drainage, as well as by various natural and industrial phenomena, industrial and municipal construction, economical and communal activity of the human. The result of such influences is addition of new substances unusual for this habitat – pollutants which directly impair the quality of water, whether it's salty or fresh. Pollutants getting into the water are as a rule qualified according to different parameters, approaches and criteria. For example, experts highlight chemical, physical and biological pollution of water. Chemical pollution is change of the chemical composition of water in a particular area and its natural qualities as a result of addition of unnatural and alien chemical substances (harmful impurities) of both inorganic (mineral salts, alkalis, acids, clay fractions) and organic nature (oil and oil products, organic remainders, surface active substances) to it. For example, tremendously harmful effect is produced by tanker wrecks after which tons of oil is spread over a vast area of water killing thousands of species of sea or ocean fauna.
