The children were considered lucky when they were admitted a place at the popular Sashigaya public nursery in Tokyo's Bunkyo Ward. Little did their parents know what a high price their young ones might have to pay for the privilege.

Two summers ago, in early July 1999, work began to enlarge a second-floor baby-care room adjacent to rooms where dozens of toddlers were being looked after during the day. Because the work site was set off only by a plywood partition, the noise and dust from the renovations filled the whole nursery.

At one point, a room next to the work site became so clouded with white dust that the children tried to run away, forcing staff to chase after them. At other times the children took naps on futon in the same room.