Experts on Thursday ruled out the possibility of chemical pollution as the cause for a mass illness that hospitalized 161 people in northeast China's Jilin Province.

A sick person receives treatment in a hospital in Jilin City, northeast China's Jilin province, May 13, 2009. More than 160 people had been hospitalized on Wednesday after exposure to unclear gas in Jilin province and investigation into the event had been launched, said the local authorities. [Wang Haofei/Xinhua]

Several thousands of people have developed symptoms of headache, nausea, muscle fatigue and seizures since April 23 after inhaling an irritant gas since April 23 in an industrial park in Jilin City, Jilin province.

All of them were workers of Jilin Chemical Fiber Co., Ltd. (JCF) and residents around the company. A total of 161 people were hospitalized, 11 of whom had been released as of Thursday.

The reactions were mainly psychosomatic, according to the report by nine experts with the Chinese Center for Disease Control and Prevention.

"Tests showed the pollutants in the air around the JCF are below the state standard," said Zhang Shoulin, head of the expert team.

"We can also rule out the possibility that the pollution comes from the neighbouring Jilin Connell Chemical Industry Co., Ltd. (JCCI)," he said. "The carbon monoxide, aniline and benzene discharged from the JCCI are all below the state standard."

"All the hospitalized are in stable condition," said Bai Huiying, Jilin City Health Bureau deputy director. "The municipal and provincial health bureaus had conducted four rounds of medical examinations for the patients."

Sick people receive treatment in a hospital in Jilin City, northeast China's Jilin province, May 13, 2009. More than 160 people had been hospitalized on Wednesday after exposure to unclear gas in Jilin province and investigation into the event had been launched, said the local authorities. [Wang Haofei/Xinhua]

The experts' report irritated the patients and their families.

"I cannot accept the conclusion," said Wang Jiping, a worker of the JCF. "Four more workers were rushed to hospitals Thursday noon. Why are there so many people sick if there is no pollution?"

"I hope experts can further investigate the cause of the sickness. We need more detailed and scientific explanations," he said.

Experts suggest doctors give psychological counseling to the patients.

The public around the company still felt the panic as of Thursday evening. Seventy-year-old resident Zhao Xin said he would not take a walk outside after dinner as is his usual routine.

"I have more than 20 relatives here in the industrial park. I'm very worried when they go to work," he said.

Part of the production lines of the JCF were suspended as workers stayed at home for fear of further illness.

Local authorities said the source of the irritant gas remained unknown.

Patients and their families believed gas came from the JCCI was to blame for the illness of so many people. The company was ordered to halt production on April 30. But no pollution has been discovered in the investigation and monitoring.

"We never discharged poisonous gas," said Wang Daxiang, deputy manager of JCCI. "The company went on trial operation successfully on April 4. There was no adverse reaction among more than 600 workers in our company."

He said the company was waiting for the official order to resume production.

(Xinhua News Agency May 15, 2009)