Mercury levels recorded in the air and surface water around the site of a fire in Hanoi last week are way over safety limits, the Vietnamese Ministry of Natural Resources and Environment said on Wednesday, contrary to an earlier report that air quality in the areas was safe.

A six-hour inferno engulfed the Rang Dong Light Source & Vacuum Flask JSC in Thanh Xuan District at around 6:30 pm on Wednesday last week, destroying approximately 6,000 square meters of the firm’s warehouses and factories.

The fire caused between 15.1 and 27.2 kilograms of mercury - used in the production of fluorescent light bulbs - to be released into the environment, Deputy Minister of Natural Resources and Environment Vo Tuan Nhan said at a government press conference in the Vietnamese capital on Wednesday.

Mercury levels recorded in the air and surface water in some areas within a one-kilometer radius from the fire are 10-30 times over safety limits set by the World Health Organization (WHO), Nhan said, citing readings from monitoring stations installed across the capital city.

Such levels are harmful to human health, he added.

Specifically, results from two monitoring stations located at the Ha Dinh Lake and To Lich River - around 1.5 kilometers downstream the site of the fire - showed the surface of these bodies of waters containing mercury levels exceeding WHO recommendations, Nhan elaborated.

Overall, water and sediment samples taken from four locations in Hanoi - all within one kilometer from the site of the fire - contained unsafe mercury levels according to standards set by WHO and in the U.S., Europe and Canada, the deputy minister added.

In addition, soil samples extracted from a flower garden at the Rang Dong Company contained higher mercury levels than other areas.

However, Nhan added that the inferno was only categorized as a “medium-scale chemical safety accident,” which calls for caution in a 500-meter contamination parameter from the fire, in accordance with WHO and European recommendations.

Last week, the National Institute of Occupational and Environmental Health (NIOEH) under the Ministry of Health said that it had conducted quick air quality tests near the fire site and found that all indicators were within safety limits.

NIOEH did note that the readings did not negate all health concerns, as heavy rains in Hanoi during the days following the incident could have affected the results.

As of Wednesday, over 100 people - including reporters, firefighters and local residents - have been examined and tested for adverse health effects at the Bach Mai Hospital in Hanoi after exposure to the air near the warehouse fire, a representative from the hospital told Tuoi Tre (Youth) newspaper.

“Most results showed mercury levels in these patients are within safety limits,” the representative said.

Dr. Nguyen Trung Nguyen, head of the Bach Mai Hospital’s poison control center, said those suffering from mercury poisoning can show symptoms including nausea, vomiting, fever, numbness in the limbs, shortness of breath, and chest tightness.

The Health Department of Hanoi said on Wednesday that it had submitted these patients’ test results to poisoning experts for feedback before making them public.

The Ministry of Natural Resources and Environment on Saturday issued a recommendation advising residents near the Rang Dong Company to clean their walls, floors and household appliances while temporarily refraining from consuming water stored in open-air tanks or farm produce grown in the areas until an official contamination zone is announced by authorities.

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