Harmful gaseous substances

Besides harmful gaseous substances, combustion engines also produce solid and liquid particles of various dimensions, consisting of a mixture of organic and inorganic compounds. The smaller particles may reside in the atmosphere even for several months. In urban areas with a high traffic density, their,concentrations in the atmosphere can be very high. 

In the sequence of emission-transport/con-version-deposition, the last phase has been dealt with in detail (Guderian 2000, 2001). Less emission leads to less deposition. Air pollutants exist as dust particles and in gaseous form, and for the effect of air pollutants their concentration in the air (immission) and their quantity deposited on receptors (deposition) is important. In ecosystems, both nutrients and harmful substances are deposited, and air pollutants may act as either acidic or alkaline, and as reductive or oxidative. The impact of immissions on plants may occur either directly (on plant leaves) or indirectly (through the soil), visible or invisible, latent or acute and chronic. Since they serve as sensitive receptors, plants and ecosystems (e.g., crops, forests, natural vegetation), soils and waters are of major interest. In order to characterize the atmospheric pollutant load of a special site in the landscape, it is first necessary to know the concentration situation and the deposited quantity per time and surface unit - the surface load. Concentrations may be measured over shorter or longer (> 24 h) periods. The concentration of gaseous air pollutants is measured in ppm, ppb or jg m. ... 

Combustion products from ferro-alloy furnaces contain extremely fine dust, formed particularly by Fe, Si, Al, Mg, and gaseous harmful substances SOj, CO and sometimes also H2S and other gases. 

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