Fires in natural ecosystems have a detrimental effect on all biota components. In the global scale, many scientific studies of prominent scientists are devoted to this topic. It should be noted that scientists have always been interested in the influence of thermal destruction of soil genetic horizons on the specific activity of radionuclides. Most of these studies began after the Chernobyl (1986) and Fukushima (2011) radiation disasters. Our research is focused on the specific activity of radionuclides due to the thermal effects of fires in natural ecosystems. It has been established that edaphotopes affected by fires are naturally restored causing the restoration of soil formation processes. The specific activity of radionuclides decreases with the duration of the ground fire. Comparing the obtained data with the regulatory documentation, it was found that they do not exceed the minimum significant activity of radionuclides in the workplace. However, the increased activity of radionuclides in soils has a detrimental effect on the ecological condition and flora and fauna development. During the fire season in natural ecosystems and forests, careless handling of fire should be avoided and preventive measures should be taken to inform the public about the harmful effects of wildfire.