So far, no deaths have been reported, it has just been learned.

All the victims were sent to nearby hospitals; 30 remain there for further care.

"Fortunately, they are out of danger already and are now getting better," said Fu Caibiao, president of the Wuyi Hospital in Wuyi County.

The accident occurred on November 15; the company has been forced to close pending further investigation.

Wu Yi Hongpeng Chemical Co. Ltd. is local. It produces aniline, an oily liquid chemically obtained from coal tar.

According to company president Pan Jinlong, at 9:20 pm, one of the workshops in the company was purifying the aniline by distillation.

Problems began when a worker turned off the vacuum system a few minutes too early, causing the boiler's temperature to soar.

Twenty minutes later, the 350-kg-substance inside the boiler got too hot, forcing one of the valves to break off. Out rushed the thick, poisonous gas.

A frightened worker jumped from the 2-metre-high operation platform and broke his legs.

More than 50 stunned workers began diluting the gas with water.

But it was too late.

The gas had spread to a nearby middle school. Students who were supposed to be going to bed were instead coughing, feeling queasy, and experiencing a headache and stomach pains.

In addition to the 500 students, an estimated 200 residents nearby felt the same symptoms.

"It was a horrifying night," said a 53-year-old victim who declined to be identified. "I smelled something very bad and then began to feel thirsty and vomit. Soon, my husband and daughter got the same symptoms."

One infected student said 36 classmates got injections at the hospital. "We have been treating most patients with Chinese traditional medicine and injections and are glad to say that no one was seriously injured," he said.

If serious, aniline could damage the patient's blood-building system and causing terrifying disease like leukaemia, said Wang Jing, an expert in occupational toxicology at Zhejiang Medical Academy.

She said it is too dangerous to build a chemical company so close to schools and residential areas.

According to the local environment protection bureau, the company has never gone through any formalities for environment protection approval. Nevertheless, it formally started its production line in October.

For reasons unknown, news of the poisoning was kept from the public until November 20, five days after it happened.

"We do not know what has taken so long for the local authority to inform us of the accident," said an official from the Zhejiang disease prevention and control centre.

He said that experts and doctors have now been sent to the county to help the victims.

(China Daily November 22, 2001)