Surging sulfur dioxide emissions on the mainland over the past five years brought economic losses estimated at more than 500 billion yuan last year, the country's top environmental watchdog says. China, the world's largest emitter of sulfur dioxide since 1995, saw emissions of the acid-rain-causing pollutant hit a record high last year of 25.49 million tonnes. This was up 27 per cent from the level seen in 2000, due to growing coal use, said Li Xinmin , a top State Environmental Protection Administration (Sepa) official. Mr Li, deputy director of Sepa's pollution control department, warned yesterday: 'Air pollution, especially acid rain, has significantly constrained efforts in achieving the goal of building a well-off society.' He said studies showed each tonne of sulfur dioxide caused 20,000 yuan in economic losses, without giving further details. But he rejected criticism that meeting Premier Wen Jiabao's target of cutting pollution discharges by 10 per cent by 2010 had become a losing battle. 'When you look at the growth of sulfur dioxide emissions in this five-year period, we have to bear in mind there was a 700-million-tonne increase in coal combustion in China. Therefore, given this background, I think a 27 per cent increase still shows it is under effective control. Otherwise, the increase could be much higher.' A total of 357 - more than half - of 696 cities and counties on the mainland under a national monitoring programme were affected by acid rain last year due to sulfur dioxide pollution. 'But the scope of acid-rain pollution areas did not expand despite situations in some areas getting worse,' Mr Li said. All rainfall in some affluent coastal areas, such as Xiangshan and Anji counties in Zhejiang and Shaowu in Fujian , was classified as acid rain. Reliance on coal has been blamed for the high emissions, with it accounting for 70 per cent of the mainland's energy consumption. Mr Li said this reliance would not be changed any time soon, as more than half the country's coal consumption was used by power plants to sustain the economy. Sepa has emission control agreements with the mainland's six largest power groups, which discharged more than 60 per cent of sulfur dioxide, and seven provinces considered key contributors to the emissions. Pilot emissions trading schemes would be launched this year in some areas, including Guangdong, to help cut pollution and improve air quality, Mr Li said. 'The objective of these measures is to achieve environmental improvement at minimal economic cost,' he said. He said air quality in mainland cities, especially Beijing, had improved last year, due to increased spending and effective measures to control vehicle emissions.