The Hiroshima Municipal Government will survey 10,000 residents to gauge the psychological impact of the 1945 atomic bombing of the city, according to local officials.

The survey will include 5,000 A-bomb survivors in the city, and all 10,000 people will be aged 60 or older.

The survey constitutes an attempt to shed light on the psychological effects of the bombing on the survivors, with these effects having yet to be sufficiently researched, the officials said.

Based on the results, the city plans to ask the national government to expand the scope of city districts designated as A-bomb-damaged areas, they said.

The prefectural and city governments of Nagasaki conducted a similar survey in 1999. The results confirmed that residents who lived outside the areas physically devastated by the A-bomb suffered a significant psychological impact.

Based on that survey, the Health, Labor and Welfare Ministry designated new areas in which residents afflicted with certain maladies are eligible for bomb-survivor-specific health checkups.

Hiroshima was to begin distributing the questionnaires Thursday.

Recipients will be asked about their experience in the bombing and whether they have since endured any psychological changes.

They will also be questioned about their health and their recollections of the "black rain" that fell on the city roughly 45 minutes after the U.S. dropped the atomic bomb at 8:15 a.m. Aug. 6, 1945.

The rain, which included radioactive fallout, is believed to have exacerbated the scale of the damage, the officials said.

The city will seek to determine where exactly the black rain fell.

The results of the survey are to be released early next year.