[en] By the data of the Military Department of former USSR the 370 underground nuclear explosions were carried out on the Semipalatinsk test site during period from 1963 by 1989. It was reported, that third part of them (100-125) have being accompanying by yield to land surface of rare gases (xenon, krypton). Starting with 1963 control for reactivity of fall out in Semipalatinsk city and some districts of the region has being conducting, and starting with 1967 definition of radioactive substances concentration in air and its isotop content has being carrying. During period from 1966 by 1988 the 15 cases of ground air contamination by iodine isotopes were registered, 11 of them were caused by explosions of nuclear devices on Semipalatinsk site, 4 - by conducting of works in China and USA. Data showing high radiobiological danger of radioactive clouds from underground explosions with excavation of soil are given. Medical surveillances in damaged settlements (1965-1970) permitted to display ray reactions of people which have surpassed expected calculation ones from given range of effective doses on external and internal irradiation. Dynamics in peripheral blood parameters and analyzer systems were revealed. Regulation activity of vegetation nervous system has been disturbed too. It was advanced a supposition, that high efficiency of population irradiation is related with combination of effects from external and internal (inhalation) irradiation from low spared radioactive cloud and precipitations on place