In the "frequency distribution of surface contamination density due to radioactive cesium by region", the surface contamination concentration in Iitate village, which is far from the nuclear power plant, is low, and the values ​​are high in Okuma town, Futaba town, and Tomioka town, which are close to the nuclear power plant.As a result, it became clear that there is a relationship between the pollution level and the distance from the nuclear power plant.As the radioactive plume passes through, dry deposition occurs in the absence of rainfall.The ventilation rate is high in Japanese wooden houses with poor airtightness, and it is considered that dry deposition occurred indoors due to the ingress of air into the dwelling when passing through the plume.

　In addition, the surface contamination of rooms, attics, and pillars of houses in the evacuation order area (Iitate Village, Fukushima Prefecture, Odaka Ward, Minamisoma City, Futaba Town, Okuma Town, Tomioka Town) was sampled by the dry smear method. Examination of "the density of surface contamination by radioactive cesium in the dwellings of each region and the distance from the Fukushima Daiichi nuclear power plant" showed that the pollution level is inversely proportional to the square of the distance from the nuclear power plant.On the other hand, no correlation was found between the outdoor and indoor air dose rates and the distance.

　The outdoor air dose rate was mainly due to the wet deposition of radioactive cesium, and since the wet deposition occurred mottled with rainfall, high deposition was observed even in the area away from the nuclear power plant.In contrast, dry deposition decreases as the distance from the nuclear power plant increases.