Substances which enter the environment unintentionally

These are in general exhalates and wastes of different origins and types. Many of them exert adverse effects on the quality of the environment, deteriorating the characteristics of the soil and the condition of the plant cover and, as a final consequence, they also affect the amount and quality of agricultural products. 

Industrial exhalates and wastes. The pollutants in the atmosphere may be gaseous, solid and (in the form of aerosols) also liquid. There are also natural exhalates in the atmosphere, e.g. from the volcanic activity. Thus, the purity of the atmosphere has been at risk ever since the development of industry, which releases many different waste substances into the atmosphere, due to imperfect technological procedures. Energy production, metallurgy, the silicate industry and of course also chemical industry are the most important producers of exhalates. 

Metallurgy produces gaseous as well as solid exhalates depending on the type of the production and technology used. Fluorine exhalates from aluminium works are very harmful, as also are tars and arsenic compounds. Iron and steel works produce fly ash, its main components being similar to those in the fly ash from coal, only with different abundances (a high 

In the field of the silicate industry, cement and magnesite works are the most important emission sources. CaO, MgO and other oxides are the main components of the fly ash. The pH is considerably alkaline the active as well as exchange pH from the emissions of cement works is approximately 

which is obviously connected with the high CaO content. 

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