[Urban environment and ultraviolet radiation].

Sanitary prognostication of the quality of urban environment covers a complex of problems, among which problems, associated with the charecter of the rational utilization of natural environment and ultraviolet microclimate regulation. Knowledge on this microclimate will help to elaborate criteria for assessment of environment, pledged in the biological effectiveness of the natural short-wave sun radiation reaching the earth surface a useful, but still poorly known environmental factor. After detailed acquaintance with the economical, physico-geographical and climatic characteristics of the big settlements in Bulgaria, 7 towns were chosen, representatives of the three basic economical regions in this country. A study was undertaken in these towns with compilation of physical characteristics of the natural ultraviolet irradiation, assessment of its biological activity and estimation of the degree of its losses in urban environment and evaluation of ultraviolet microclimate changes, in view of the possibilities to formulate an environment constituting a danger to health. The results may be helpful for a broad circle of specialists, occupied with environment protection problems and with the aspects of rational urban planning.