The clouds of toxic smog that hang over the Pearl River Delta and Hong Kong are no secret, but where exactly do they come from and how bad are they? Post reporter Cheung Chi-fai and photographer Robert Ng went to the heart of the delta's industrial zones to find out for our three-part investigation starting today Yuelisha village in Nanhai could easily be the place the song Where Have all the Flowers Gone? was written about. It used to be surrounded by beautiful rose farms. But many have gone since the Guicheng power plant was built next to the village more than a decade ago. Black smoke and dust from the plant killed the flowers and pollution made the soil increasingly unsuitable for growing flowers. The village, with a few hundred residents, is sandwiched between the power plant and a nearby aluminium smelter operated by a Hong Kong-listed company. 'There are tiny black particles falling on the farms from time to time and it makes us choke,' said 60-year-old villager Wu Runshui . 'At night we have to close all the windows for a good sleep.' The medium-sized, oil-fired Guicheng plant has 12 generating units of unknown capacity. Smokestacks have been raised so the pollutants can be pushed further away from the farmland. But a month ago, the plant was identified by the Guangdong Environmental Protection Bureau as one of the worst 33 polluters in the province and told to make improvements. It is understood the plant has been ordered, along with a group of smaller power plants, to close by 2007 under a provincial plan to shut less efficient plants to improve air quality. Villagers said the plant was to have been closed years ago but the plan was delayed indefinitely. 'It should have gone but nothing happened,' Mr Wu said. 'We heard the plant management knew some powerful people and successfully preserved the plant.' Last year, Guangdong cited the province's rising power production as the main cause of the region's deteriorating air quality, a view echoed by Hong Kong's environment officials. Extra generating facilities were installed last year to raise capacity by 1,350MW, allowing for a 17 per cent increase in electricity generated to 188 billion kWh, the province's environmental quality report revealed. Some smaller plants, which should be shut down under existing regulations, are said to be operating secretly to meet demand. 'These small local plants are highly flexible and operate in response to market demand when there is a power shortage,' a mainland source said. Another source said some smaller plants had switched to heavy oil with higher sulfur content amid higher prices. 'The high oil price has forced them to use poor quality fuel, which causes much more air pollution,' he said.