The environmental impact assessment for a controversial chemical project was made public on Tuesday in the latest move to dispel residents' fears by the plant owner and city authorities in Kunming.

Released on the website of the China National Petroleum Corp, the company behind the refinery project also known as CNPC, the report says the environmental risks are acceptable and all pollutants discharged can be recycled or filtered to be made harmless.

"We invested about 3.2 billion yuan ($521 million) in installing facilities to protect the environment - about 15 percent of the total costs," Hu Jingke, general manager of the company's Yunnan Petrochemical, told China Daily.

The environmental protection bureau in Kunming, the Yunnan provincial capital, said it will make every effort to supervise the project during and after construction.

Inspections will be made at least once a month, with experts, residents and the media invited to the site, the bureau said, promising to release information on the construction progress every three months.

"We will establish long-term communication with the public, collecting their opinions and releasing information in a timely manner," said Li Wenrong, the city mayor. Li added that he has learned that authorities should not make decisions before consulting the public.

In May, hundreds of Kunming residents took to the streets to protest against the refinery being built, concerned it would produce paraxylene, or PX. The plant will be about 27 km from Dianchi Lake, one of Yunnan's major attractions.

Hu emphasized at a news conference in May that the project did not produce PX.

Mayor Li also said in a previous report that the government would listen to public concerns and call off the whole project if "most of our residents say no to it".

Ma Jun, director of the Institute for Public and Environment Affairs, said the fact that the assessment did not cover information about PX may mean that the government has not started a PX project, but at least it is a good start for information transparency.

The assessment report said the plant will process 10 million metric tons of oil annually, while emitting 2,513 tons of sulphur dioxide and 1,272 tons of nitrogen oxide, and discharging 1.23 million cubic meters of wastewater.

The refinery is expected to be completed in 2015, supplying 53 percent of oil consumption in Yunnan and handling oil from a strategically important pipeline being built across Myanmar, which is due to open this year.

The assessment said all wastewater and pollutants will be filtered or recycled before being discharged into rivers or sent to Kunming's hazardous-waste disposal center.

However, the report and the supervision plan have failed to dispel some people's doubts.

Resident Gong Hong said: "The assessment answers some of my questions, but what I'm worried about now is if CNPC can do what the assessment says, and whether the authorities can play their supervisory role well."

Yang Chaofei, vice-chairman of the Chinese Society for Environmental Sciences, told Science and Technology Daily that the lack of confidence in the local government is mainly due to the fact the authorities do not seek public opinion before conducting environmental impact assessments.

"Without collecting public opinion, residents will question the government once they find out that construction has started on a plant nearby," he said.

Large protests have been staged against several chemical projects in China in recent years.

In November, the government in Ningbo, Zhejiang province, called off a petrochemical project after days of street protests, while demonstrators in Dalian, Liaoning province, also turned out after the authorities announced plans for a PX plant in 2011.