‘Black rain’ accounts spark expert call to reset Nagasaki A-bomb survivor recognition area

An expert is calling on the Japanese government to reexamine contamination conditions in areas surrounding the city of Nagasaki following the Aug. 9, 1945 atomic bombing. The call comes after a survey of A-bomb survivors’ experiences showed a concentration of stories about ash and “black rain” in a community some 20 kilometers from the hypocenter — well beyond the zone designated by the health ministry for survivor support.

The government issues “hibakusha” A-bomb survivor handbooks to people within around 7 km east-west and approximately 12 km north-south of the Nagasaki hypocenter. The handbooks entitle the bearers to special health benefits to cover damage inflicted by the bomb and its aftereffects.

However, the geographical limits on coverage have long excluded settlements where residents claim to have been exposed to fallout and “black rain,” or rain contaminated with radioactive ash from the atomic explosion that devastated the southwest Japan port city.

The Mainichi Shimbun examined the results of a Ministry of Health, Labor, and Welfare survey released this June of atomic bomb survivors’ experiences, and found 32 accounts mentioning the black rain and ash in what is now central Isahaya, Nagasaki Prefecture, about 20 km east of where the A-bomb detonated.

One expert has pointed out that “there are numerous accounts from similar locations. And it’s not just the rain, but also ash containing radioactive particles that could cause internal exposure and health damage. The government should investigate the conditions outside the designated areas more thoroughly.”

A July 2021 ruling by the Hiroshima High Court recognized 84 individuals who experienced “black rain” from the Hiroshima atomic bombing as hibakusha, including those who were about 30 km from the hypocenter, citing the potential for health damage from inhaling radioactive particles, or consuming contaminated water or vegetables. Following this, the government began issuing atomic bomb survivor handbooks to those who encountered rain outside the set support areas in and around Hiroshima.

Meanwhile, since 2002 the government has been assisting those who were about 7-12 km east-west of the Nagasaki hypocenter by covering medical expenses for mental illnesses and related symptoms, designating them as “atomic bomb experience survivors.” These people argue that they too might have ingested radioactive particles and suffered health effects, seeking to obtain formal recognition as hibakusha and the accompanying handbooks. However, the government has not recognized them, citing a lack of objective rainfall records.

Responding to requests from Nagasaki Prefecture and the city of Nagasaki to expand the scope of aid, the health ministry investigated A-bombing witness accounts stored at facilities including the Nagasaki National Peace Memorial Hall for the Atomic Bomb Victims. They found 41 accounts mentioning rain and 159 mentioning ash or other fallout among 3,744 accounts documenting experiences outside the bombed area. The highest concentration of experiences involving rain and fallout was in Isahaya, with 17 mentioning rain and 60 stating fallout.

Reviewing these accounts in June and July with cooperation from professor emeritus of physics Masato Oya of the Nagasaki Institute of Applied Science, the Mainichi confirmed 200 accounts mentioning rain and fallout. Of the 77 accounts from Isahaya, at least 32 (12 rain, 20 fallout) were concentrated in the city’s center, with 13 from the prefectural agricultural school and 11 around Isahaya Station. The ages of those recounting these experiences ranged from 10 to 32 years at the time of the bombing.

A man who was 16 years old and was at the agricultural school when the blast struck described in his fiscal 1995 account that “about one to two hours after the explosion, the clear sky turned black, and suddenly heavy rain mixed with black particles fell.” A woman who was 19 and working at the Isahaya branch of a naval hospital wrote in her own fiscal 1995 account that “burnt paper scraps and rag-like debris kept flying around. Because it started raining, we brought medical supplies indoors.”

The health ministry concluded that it could not consider the rain and other phenomena as objective facts, based on expert opinions that these accounts “lacked reliability as data” and might be “embellished memories.”

Meanwhile, Oya, an expert on Nagasaki atomic bomb fallout, stated that the accounts are detailed and credible, indicating that rain and ash fell over a wider area than the 12-kilometer radius that has been the starting point of discussions thus far. He emphasized that the government should face the facts, collect more data, and clarify the true extent of the atomic bomb’s impact.

(Japanese original by Arina Ogata, Takehiro Higuchi, Nagasaki Bureau; and Deockwoo An, Hiroshima Bureau)