Zengcheng City - as anyone making the rail journey from Hong Kong to Guangzhou may know - claims one of the mainland's highest concentrations of cement factories and arguably Guangdong's most polluted air. As of the end of last year, this satellite community, 60 kilometres south of the centre of Guangzhou, was home to 110 cement-makers - observable to rail travellers by the red-brick kilns belching plumes of smoke and cement dust trackside and across the city of 750,000 people. The factories, most of which have been operating at a loss for the last two years, are reminders of the environmental difficulties created by Guangdong's prosperity. While the provincial economy has doubled and doubled in 20 years, the air, water and land have been left degraded and in serious need of rehabilitation. Provincial officials are taking notice and starting to do something about it. Since January, 40 Zengcheng cement-producers have been closed, as part of national and local efforts to rid over-production from struggling manufacturing sectors - such as cement manufacture - as well to shut down the country's worst environmental offenders. Ye Zhirong, of the Guangdong Environmental Protection Bureau, says more will follow, with all Zengcheng cement factories producing less than 44,000 tonnes annually to be closed by the end of next year. Moreover, the province is preparing to close the hundreds of small coal-burning power plants that were commissioned to meet Guangdong's electricity shortfalls. Ms Ye said: 'We are trying to reach sustainable development. Although the quality of the environment is undoubtedly worse than it was in the 1970s and 1980s, Guangdong has avoided the situation of rapid environmental deterioration.' Such claims are debatable. Despite outlays over the past 10 years of 200 million yuan on public-works projects, soil and water erosion due to construction, mining and road-building remains pervasive. Guangdong's Environmental Protection Bureau estimates that 8,242 square kilometres of provincial land is in need of immediate treatment. Water, particularly in the Pearl delta, is filthy. Much of this is due to the poor attempt to filter household waste water, with treatment rates province-wide standing at 12 per cent of the more than three billion tonnes of home waste water dumped last year. This compares with the 80 per cent treatment rate for the province's 1.25 billion tonnes of industrial water, and has led to increased organic pollution in municipal water supplies, particularly in Shenzhen. Guangdong's air is also foul, due in large part to unbridled coal burning. The Guangdong bureau estimates that more than 50 per cent of all rainfall is acid rain. The result has been the death of thousands of acres of forests and crops, accelerated soil erosion and the weathering of power lines and buildings. Guangdong places acid rain losses at four billion yuan (about HK$3.72 billion) per year. The incidence of acid rain is particularly prevalent in the province's main cities, with Guangzhou boasting acid rain frequency of 72 per cent. Urban acid rain is primarily attributable to emissions from cars and, in particular, motorcycle emissions, Ms Ye said. In 1996, 72 per cent of all motorised vehicles in Guangzhou were motorcycles. 'They are just like locusts,' she said. Pilot schemes, like the one aimed at closing most of Zengcheng's cement factories, represent a significant step forward for Guangdong's efforts to improve the environment. Significantly, the province has indicated it is prepared to match high policy goals with down-to-earth funding, raising environmental spending from 0.64 per cent of gross domestic product prior to 1995 to 2 per cent of GDP by the start of the next decade. Important to the clean-up efforts is a provincial Green Water Scheme, involving 115 projects, 15 of which are targeting large rivers and lakes. The goal, Ms Ye said, was that by 2005 sewage treatment plants would be started in every city, with 40-45 per cent of domestic sewage treated.