The mainland's environment is worsening, according to officials at the State Environmental Protection Administration (SEPA) in Beijing, and disregard for safety is widespread. Yet even so, the proposed Xiamen PX plant - as locals dub it - stands out for the scale of investment, its proximity to human population, the danger of the chemical and the complexity of the political issues involved. Observers in Beijing say these factors make it a test case of the central government's recent publicised resolve to balance GDP with environmental considerations and vows to improve safety, and are watching closely.

What also stands out is a media black-out. Local reporters say they have been muzzled since it was launched in November. Chat sites that sprang up briefly in the early spring have been taken down. Local opponents say they have been taken in to 'drink tea' with the police and warned off; others are simply not going home, to avoid intimidation.

Blogger Lian Yue, who wrote extensively about the plant earlier this year, said authorities shut down his website on May 11. 'I don't know why they blocked it, they never tell you, but it's a fair guess it was because of that,' said Mr Lian. 'As a Xiamen resident, I must speak out. You can't complain about the environment and then not do anything when something like this happens where you're living.'

Yet there are signs the black-out is beginning to fail. As Professor Zhao's campaign gathers momentum, helped by Mr Lian and others, Xiamen residents are taking notice. On Friday some plan to gather outside the city government offices in silent protest.

The scenario that has opponents spooked happened in Jilin province in November 2005, when a massive explosion in a PetroChina benzene plant - a material related to p-Xylene - killed eight workers, injured 60 others and spilled tonnes of the carcinogen into the Songhua River, forcing the closure of water supplies in cities downstream and spreading panic in Harbin.

Critics of the Tenglong factory say that despite its evident drawbacks, a heady mixture of greed and ambition is pushing it forward.

Chief among supporters is Xiamen Communist Party secretary, 52-year-old He Lifeng , who Professor Zhao says is keen to nearly double Xiamen's annual GDP from its present 110 billion yuan to 200 billion, something the government believes the Tenglong plant will achieve. Locals believe Mr He has ambitions for a transfer to the central leadership, meaning he must make province-level party secretary or governor before turning 60. Doubling Xiamen's GDP will help his case, they maintain.

Professor Zhao dismisses that as a get-rich-quick fantasy that reflects the mainland's pursuit of higher GDP at any cost. 'It's nonsense. They won't have that capacity. How will they even provide the energy for it? Mission impossible,' she said.

The plant will need more than 5,000 tonnes of coal per day, she says, reportedly to be shipped from Indonesia. In order to handle the throughput it is building a pier in southern Haicang just for coal. The pier is sited in the middle of the White Dolphin Nature Reserve.

'We haven't seen a white dolphin here for at least seven years,' said local resident and plant opponent Guo Minmin. 'But isn't it crazy?'

Xiamen's propaganda department declined to answer questions and rejected a request to interview Mr He. 'We are going to examine this problem, maybe later,' said a spokesman. 'Right now it's not convenient as it touches on national issues.' Among those is the fact the plant was approved in July 2006 by the National Development and Reform Commission, China's top body formulating policy on economic and social development. The size of the investment made NDRC approval necessary.

Others speculate that Chen Yu-hao's Taiwan identity makes the project deeply political, with the mainland keen to forge closer economic ties to the island across the Taiwan Strait from Xiamen, in the hope of speeding unification. 'There are projects, such as the Beijing-Lhasa railroad, that the government will okay because they are politically important, even though they are environmentally destructive,' said one environmental lawyer.

Complicating further an already complex picture, Chen is wanted by Taiwan authorities. 'We issued an arrest warrant in 2003 after he failed to appear in court to answer questions about embezzlement, and as far as we know he hasn't been here since then,' said a Taipei District Court spokesman. 'If he comes back here he will be arrested.'

The spokesman would not confirm the size of the suspected embezzlement, believed to be from one of Chen's own companies in Taiwan, but Taiwan news reports at the time put it at more than NT$800 million (HK$190 million).

Tenglong spokeswoman Susan Su refused to comment. 'We know there are people asking questions, but we're not ready to say anything,' she said.

Locals may be largely in the dark about the plant and what it will manufacture, but some can already see a problem. Shucking oysters outside her family's small shop in Jianmei village, about one kilometre from the projected site, Mrs Li complains about fumes from Xianglu, a neighbouring plant - also owned by Chen - that seep out, especially at night. That plant produces PET, which is used to make drinking bottles and other plastic items. 'We get itchy skin and it smells bad,' she said, scratching her leg for emphasis.

Mrs Li's daughter emerges from the shop, carrying her daughter, eight-month-old Linlin, on her hip. 'We often can't open the windows at night because the smell is so strong,' said the younger woman. 'And it's hot at night.'

Xianglu is a downstream plant that uses p-Xylene to manufacture PET (polyethylene terephthalate) used in beverage, food and other liquid containers. Professor Zhao believes that by building an upstream, p-Xylene plant next door, Chen hopes to significantly increase efficiency and profits.

For now, the factory is just an expanse of red earth. In neighbouring Ningdian village, perched at the edge of the site, village chief Li Lucai, 56, said: 'If there is any kind of explosion there we're all dead. All the way to the sea.'

Low levels of p-Xylene exposure cause skin irritation, breathing problems and headaches, while greater exposure causes liver and kidney damage and may cause cancer. P-Xylene is related to benzene, known to be carcinogenic, and is a widely used chemical found in solvents, paints and varnishes.

'It's quite a dangerous chemical, especially if it is close to a residential area. It's very flammable and that's its main risk,' said David Santillo, senior scientist at Greenpeace Research Laboratories in Britain.

P-Xylene's flash point is just 27 degrees Celsius. Xiamen summer temperatures average more than

30 degrees.

European guidelines for dangerous chemical plants - dubbed the Seveso Directive, after an accident at a chemical plant in Seveso, Italy, in 1976 that led to the release of large quantities of deadly dioxins - stipulate they be built far from human habitation. Elsewhere in Asia, p-Xylene plants in Malaysia, South Korea and Thailand are between 52km and 238km from population centres, while mainland plants average about 20km.

Mr Santillo said companies generally justified projects by pointing to multiple safety measures, but that was not enough. 'It only takes one person to make a mistake. They have to site the place properly,' he said.

After the Jilin explosion, SEPA sent inspectors to check major chemical facilities nationwide and in February 2006 drew up a blacklist of 127 companies. Both the proposed Tenglong and the existing Xianglu plants are on it, deemed as needing improvements and carrying explosion and fire dangers.

In mid-May Professor Zhao travelled to Beijing to meet Li Ningning, a deputy director of the NDRC, to press her case. She returned empty-handed. According to Professor Zhao, the official pointed out that SEPA approved the project in July 2005, on the back of an earlier Environmental Impact Assessment, commissioned by Tenglong, Beijing Huanqiu Contracting and Engineering Corporation.

Huanqiu, a wholly owned subsidiary of state-owned China National Petroleum Corporation (as is PetroChina, owner of the Jilin plant), specialises in chemical engineering projects. Calls to the company were not answered, nor was an e-mail with questions.

A SEPA spokesman declined to provide a copy of Huanqiu's environmental report, even though mainland law states at least an outline should be available on request. The spokesman, who declined to be named, referred questions to Xiamen's environment authorities, who referred questions to Haicang district authorities. Xu Huohui, director of the Haicang environment protection administration, referred questions back to SEPA in Beijing, saying they had approved it. Mr Xu said he didn't have a copy of the EIA.

'It is a major flaw in our environmental protection system that the company building a factory commissions the environmental impact assessment itself,' said Zhang Jingjing, a lawyer at the Centre for Legal Assistance to Pollution Victims in Beijing.

Meanwhile, if all else fails, Professor Zhao plans to write a personal letter of protest to President Hu Jintao.

'We aren't saying, 'don't build this plant',' she said. 'We are saying, 'build it 100km away'.'