Modelling and observations of biologically active solar UV radiation: towards balancing between health risks and benefits

Studies of the UV-radiation are the most actual ecological problems that are called by ozone depletion increasing the level of biologically active solar UV-B radiation in the biosphere. The air pollution and atmospheric aerosols prevent penetrating appropriate dose UV radiation, which is beneficial for people, specifically due to production of vitamin D3 in skin from its precursor 7dehydrocholesterol. Both factors define necessity of the control of the UV-radiation terrestrial level. Many physiologic genetic and biochemical cell parameters change under the UV radiation impact. Thus the UV-radiation is the active bio-regulator. Here we elucidate the synergic biologic interaction with biologic objects, for natural conditions of the solar UV irradiance, various atmospheric state and with different lightning geometry. In addition, we present here reliable algorithm for direct calculation of the vitamin D synthetic capacity of sunlight using the photoreaction model of vitamin D synthesis with solar UV-spectra at the input.