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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. |
Inorganic pollution of water
The major inorganic pollutants of water (both fresh and salty) are various chemical compounds that are toxic for the fauna of the aquatic environment. Among them are arsenic, lead, cadmium, mercury, chrome, copper, fluorine compounds. Most of these pollutants get into water reservoirs as a result of human activity. Thus, metals are being taken up by phytoplankton and then are transferred all the way up the food chain to more developed organisms. The toxic effect of some of such chemical elements is tremendous.
In addition, various inorganic acids and bases causing a wide range of pH of the industrial drainage and able to change the pH of the water environment to over 8.0 should be also taken as very dangerous pollutants whereas fish and other organisms are able to live only within the range of pH 5.0-8.5.
Enterprises of the food industry and agriculture are among the major sources of pollution of the hydrosphere by mineral substances and biogenic elements. For example, more than 12 million tons of salt is washed off the irrigated lands every year and this figure is increasing. Waste products containing mercury, lead, copper are mainly localized in certain areas, but some part of them is being transferred far beyond territorial waters. Thus, pollution with mercury leads to restraining the development of the phytoplankton. Wastes containing lead are usually laid in ground sediments of bays and estuaries of rivers. Its further migration is accompanied by further accumulation of methyl lead and its further addition to trophic chains of water organisms.
