Standing at the front of a dimly lit room in the basement of the Hiroshima Peace Memorial Museum, Teruko Yahata's voice broke as she recalled the morning her world changed, on Aug. 6, 1945.

"All of a sudden, the entire sky flashed and was illuminated in bluish-white, as if the heavens had become one huge, fluorescent light," the 85-year-old, speaking in English, told an audience of British tourists on May 9.

"I immediately fell to the ground and lost consciousness."