Study into epilation among residents and "black rain" fallout in the Manose district of Nagasaki City following dropping of the atomic bomb

Abstract

It became clear from the testimony of residents that a considerable amount of black rain fell in the Manose district of Nagasaki City The Manose district is a small settlement located in a mountainous area approximately 7.5 km northwest from the hypocenter. Not only did black rain fall, but the residents experienced high incidence of epilation. Soil sampling aimed at detecting plutonium originating from the atomic blast was conducted primarily in the Manose district in July 20 II. The black rain in the Manose district is a valuable incident in terms of determining the effects on the human body of low-level radiation exposure, and further analysis appears needed. INTRODUCTION At II :02 am, August 9, 1945, an atomic bomb was dropped on Nagasaki, and detonated at an altitude of 500 meters. The weather in Nagasaki at that time was sunny and clear. A light wind was blowing from the southwest. Large amounts of black ash and dust from the atomic bomb were carried eastward by the wind. Residents in this district consistently reported that the bomb explosion was followed by a shock wave. After that, the sky turned black, and the sun hung reddish-black. Much ash, dust, and debris fell from the sky (Figure I). Figure I. The picture which residents drew Figure 2. The map of Nagasaki Approximately 20 minutes after the bomb was dropped, rain fell in the Nishiyama district of Nagasaki. Subsequent investigations measured high levels of radioactivity in the Nishiyama district, and amounts of lifetime radiation exposure are estimated at 200 to 400 milligrays. This corresponds to approximately 10 times the amount of radiation in the Hiroshima districts of Koi and Takasu, where black rain similarly fell following the atomic bombing there.