While the protest was triggered by the fact that locals felt betrayed when the plant was allowed to be built without their knowledge and operated illegally for months despite safety and pollution risks, Professor Zhu Lijia, from the Chinese Academy of Governance, said it was a serious warning to local authorities.

'Locals in Dalian not only marched against the chemical plant and local authorities' handling of the spill scare, but also wanted to vent their anger at the government's crumbling credibility,' he said. 'The message is simple - the people are discontented and they simply don't trust the government.'

Zhu and other analysts said how the controversy unfolded remained to be seen, with residents not convinced by the pledges to relocate the plant, which mentioned no timetable or details such as relocation sites.

'Mainland authorities too often give empty promises in the face of public pressure, but later eat their words after the outrage ebbs,' Zhu said. 'Mainlanders simply know these kind of stalling tactics too well.'

Analysts were positive about the domino effect the Dalian protest may cause in other mainland cities, where environmental concerns still take a back seat to political interests and economic growth when governments make decisions on major chemical projects. Few people may have heard of the toxic chemical paraxylene, also known as PX, which the Fujia plant produces, before the spill scare broke out a week ago.

But according to the 21st Century Business Herald, citing government statistics, there are at least 11 PX projects either being built or already operational across the mainland, mostly close to populated areas in big cities, including Shanghai, Nanjing, Qingdao, Urumqi and Tianjin .

Whether it is carcinogenic or not remains a question even for scientists from America's Environmental Protection Agency, but it can damage the central nervous system, liver and kidneys in cases of large exposure.

Professor Zhao Zhangyuan , a researcher at the Chinese Academy for Environmental Planning, said it was reasonable for the public to fear the accumulated effect of a toxic chemical manufactured some 21 kilometres from the city centre. 'It is the proof of the rise of environmental awareness,' he said.

Professor Ai Nanshan, an environmental scientist at Sichuan University, said the protest in Dalian would encourage people in other cities to care more about their safety when living alongside PX projects and voice their concerns.

'I hope to see the domino effect of the Dalian protest although we know that's the worst fear of the stability-obsessed mainland authorities,' he said. Ai said local authorities may try to crack down on such environmental activism because they were driven by huge economic interests when pursuing PX projects and other large petrochemical plants.

Zhu agreed. 'Further protests look inevitable ... public environmental awareness has increased greatly as a result of the Dalian protest and another demonstration in Xiamen a few years ago,' he said. The Xiamen authorities were forced to scrap a PX project in 2009 after thousands took to the streets.

'As long as the government has yet to translate its promises about changing its energy-intensive and heavily polluting growth mode into actions, we will see more mass demonstrations,' Zhu warned.