Abstract: Due to the increase in radon emanation, the conductivity in the surface layer of air increases, which causes variations in the electric fields in the low atmosphere and according to some hypotheses in the ionosphere. There are well-known proposals on the possibility of using such ionospheric disturbances as precursors of earthquakes. In this study, the ionospheric electric fields are calculated in the framework of a quasi-stationary model of the conductor consisting of the atmosphere, including the ionosphere. The consequences of the paradoxical point of view on the decrease in the conductivity of surface air with an increase in radon content are also considered. It is shown that even with extreme radon emanation, the obtained calculated perturbations of the ionospheric electric field are three to four orders of magnitude smaller than the supposed precursors of earthquakes.