This paper reports the results of environmental studies conducted in May‒June 2021 in 16 prefectures of Japan, over which radioactive clouds spread as a result of the accident at the Fukushima-1 nuclear power plant in March 2011, namely: Aomori, Miyagi, Fukushima, Niigata, Ishikawa, Ibaraki, Kanagawa, Shizuoka, Osaka, Kyoto, Okayama, Tottore, Shimane, Kagoshima, Nagasaki, and Ehime. Some effects of the impact of accidental emissions of BWR-3 and BWR-4 reactors on the environment in the settlements neighboring the Fukushima-1 nuclear power plant were summed up. The methods of conducting research are described, starting with a sampling of environmental objects in the above prefectures (atmospheric air, soil, vegetation, agricultural products, sea and ocean water, and aquatic fauna) and sample preparation up to measurements and data processing to obtain results and their subsequent analysis. A comparison of the results of research with the volumes of emissions of radioactive substances due to the normal operation of various objects for the use of atomic energy was carried out. Conclusions are drawn about the medium-term (after 10 years) consequences of the nuclear accident at the Fukushima-1 nuclear power plant. The maximum background radiation equal to 2 µmSv/h observed at point No. 83, 20 km from the Fukushima-1 nuclear power plant, will not lead to irradiation of a person with doses exceeding the permissible limits if the time of his stay at the reference point is limited to 1.36 hours per day. The concentration of cesium-137 in the water of Japanese waters does not exceed the level of the radiation factor, upon reaching which protective intervention is necessary. The maximum specific activity of cesium-137, detected in soil and vegetation samples near the Fukushima-1 nuclear power plant, does not exceed the maximum specific activity (MZUA). In Japan as a whole, the specific activity of radionuclides in soils used for agricultural production and livestock grazing does not exceed the levels of global pollution.