The Rang Dong Light Source and Vacuum Flask JSC, whose warehouse had caught fire on August 28, had previously reported to the authorities that it had been using Amalgram (an alloy of mercury with other metallic elements) in lieu of liquid mercury for its light bulb production since 2016.

The company’s head has since admitted that all 480,000 fluorescent light bulbs that were burnt in the fire had liquid mercury in them.

This was confirmed by on-the-field examination by the Vietnam Environment Administration under the Ministry of Natural Resources and Environment, the agency said in its Sunday report.

"It is estimated that between 15.2 and 27.2 kilograms of mercury have been released into the environment," said Hoang Van Thuc, Deputy Director General of Vietnam Environment Administration.

The report also said within a 1,000-meter radius of the fire, the amount of mercury in the air was at a level acceptable under Vietnam’s national environmental standards as well as that of the World Health Organization (WHO).

Inside the warehouse area, the mercury level had exceeded WHO warning levels by 1.532 times, as opposed to the 10-30 times announced earlier by the Deputy Minister of Natural Resources and Environment, Vo Tuan Nhan, at a press conference last Wednesday.

Thuc of Vietnam Environment Administration had said last week that evacuation of residents within a 500m radius of the fire site was not necessary.

He said the residents in these areas should wear masks and long-sleeved clothing whenever they get near the scene of the fire.

People within the 500m radius can get free health checks from the municipal Department of Health, Nguyen Duc Chung, Chairman of the Hanoi People’s Committee, had said last week.

He had also said that the Rang Dong company will be responsible for dealing with pollution in the area of the fire, and would have to provide authorities with information on the origins of mercury stored in its warehouse, as well as other documents relevant to its storage.

A five-hour blaze that started at 6 p.m. on August 28 destroyed a third of the inventory at the 6,000-square-meter warehouse belonging to the Rang Dong company in Thanh Xuan Trung Ward in the southwestern Thanh Xuan District.

Initial investigations show that the cause of the fire stemmed from storage procedures and there was "no sign of sabotage," Chung said. The exact cause is yet to be determined.

Residents near the fire had started moving out of their homes the following day due to health concerns. Several people reported unusual fatigue and stinging eyes.

Rang Dong, a leading manufacturer of lighting products and equipment, has estimated the loss from the fire at VN150 billion ($6.4 million).