About 130 workers from six factories in the capital’s Vattanac Industrial Park II fainted on Friday and Saturday, incidents officials blamed on the health of the workers and hysteria, despite complaints of poor ventilation.

“We did not smell any chemicals or see any problems with their working environments,” said Teun Bunthen, police chief in Dangkor district’s Kraing Pongro commune.

Workers had been taken to nearby health clinics, and authorities were continuing to investigate, Bunthen said.

A Ministry of Labour official who asked not to be named said chemicals or poor ventilation was not to blame, but rather many workers had experienced a “mass psychogenic illness” – a sort of shock – when confronted with others fainting.

But Veng Vuthy, deputy director of Porng Teuk Health Centre, said workers had reported a strong chemical smell.

“There are many reasons for their fainting,” he said.