Critical levels for effects of air pollution on materials

Atmospheric deterioration of materials is the result of the combined action of different environmental factors including pollution that stimulates the processes. Damage function describes the environmental impact on materials. They allow to quantify the effect of pollutants on particular properties of material. At the present state of knowledge damage functions are only available for few groups of materials, such as structural metals. Deterioration mechanisms are specific for different groups of materials, for different types of pollution and their combinations. The definition of a generally valid critical level for all materials together on the base of scientific knowledge is therefore impossible. For practical and technical purposes - the rational use of materials - it is necessary to characterize atmospheres by classified categories of pollution levels and other important factors. Attached information (guiding values) about the extent of deterioration or decrease of life time on the basis of available dmage functions may be given