When the Nato bombs started to fall on Pancevo's petro-chemical factory, 10 miles east of Belgrade next to the Danube in Serbia, the locals thought it must be a mistake. Surely, even in war, no one would risk releasing deadly chemicals less than two miles from a city.
But, as the attacks continued, it was clear that they were being aimed at storage tanks that contained the raw materials for PVC.
As the air strikes continued, heroic efforts were made to load them into rail tankers to save the civilian population. But it was all in vain - 80,000 people were exposed to a dose of one chemical 10,500 times above the safe limit.
At the height of the Nato offensive, the bombing of Pancevo was seen as a victory against a strategic target because of its spectacularly burning oil refinery, with only a footnote of regret about the contamination of the canal that feeds into the Danube.
But two years on, the long-term damages caused to the city, its people and their water supply are only now being fully realised and dealt with. The UN Environment Programme (Unep) and the city are desperately trying to scrape together the funds to save the area from continuing environmental disaster.
Already, 100 workers who tried to stop the leaks and limit the damage of chemicals flowing into the ground have been declared permanent invalids because of lung damage. A number of young men have had unexplained heart trouble.
Two years after the bombing, despite two winters of heavy rains to cleanse the soil, still nothing grows around the petrochemical works. The earth has patches of dark-green algae in puddles but no other life; elsewhere, the countryside is alive with verdant growth.
The newly elected mayor of Pancevo, Borislava Kruska, a quietly spoken woman, says by the time Nato experts had arrived months after the bombing, the chemicals on the surface, which were causing air pollution, had evaporated.
Most of the chemicals, however, remain just below the surface.
"It is what I call the perfect murder. Nobody will be able to prove what killed us," she said. Unep says a saturation level of one part per million of vinyl chloride monomer (VCM) in the air is enough to trigger cancer of the liver. It can cause brain tumours and attacks the nervous system.
In Pancevo, the saturation reached 10,500 parts per million.
It is too early to see the effects on the human population, but there are alarming signs that something is wrong: A rare bone cancer, previously restricted to very old dogs, has being found in abundance in puppies and adolescents.
And VCM is not the mayor's only worry. There is another PVC chemical, 1,2-dichloroethane (EDC), which is highly toxic and particularly attacks the liver and kidneys. At least 2,000 tonnes of it leaked into the ground after the bombing.
Eating all root vegetables in Pancevo has been banned and tests show that EDC has penetrated deep into the ground, close to the city's water supply.
A group of experts from several countries is trying to work out how to recover the EDC before it reaches the water table. An estimated 130,000 people use the local water pumped from the ground.
Unep estimates that the pollution problem will cost £14m to fix; so far it has raised £4.5m from the international community that bombed Pancevo. Holes will need to be drilled to pump out the contaminated water before it reaches the water table.
The canal, which runs from the bombed water-treatment plant at the factory to the Danube, needs £4m worth of dredging to prevent the contaminants leaking into Europe's longest river.
Some urgent remedial measures have been taken. In one area, Unep has removed 80cms (31.5in) of topsoil to collect most of the eight tonnes of mercury released by the bombing.
The technical manager of the factory, Dmitar Krivokuca, who is working with UNEP on the clean up, said: "There has been some poisoning of our workers and people are in jeopardy the whole time, but we have to clear this up if we are going to restart and provide employment."
The neighbouring oil refinery has started work again providing the first jobs in an area that had 10,000 industrial workers before the war.
The smell of sulphur now dominates from the cheap Russian oil being processed, but filters will be fitted when funds permit.
The mayor said: "We are not pretending that before the bombing the area was not polluted, it was, but not on this scale.
"As we go on living and dying in Pancevo, we will never be able to prove what is killing us. No population has been exposed to this level of these chemicals anywhere in the world. What we need is help to stop it getting worse."
© Guardian Newspapers Limited 2001