The environment watchdog is poised for another head-on clash with power suppliers as it proposes phasing out old coal-fired generation units to meet an international convention on toxin control. The plan aims to fulfil the Stockholm Convention on Persistent Organic Pollutants that bans or limits the production and release of 12 toxins, including pesticides and dioxin. Hong Kong has to submit its implementation plan on the curbs this year via Beijing, a signatory to the convention. The proposed move comes at a sensitive time as CLP Power is locking horns with the government over plans to reform the electricity market and associated environmental requirements. At the core of the potential new row is the release and production of cancer-causing dioxins and furans - two by-products emitted into the air and left in the ashes from burning coal. It is estimated that the power companies could have contributed 26 per cent of the dioxin and furans produced in 2003, following metal production (39 per cent) and land-filling (28 per cent). In the draft plan, the government says it may propose phasing out old coal-fired generation units and replacing them with gas-fired units within 10 years of the policy being implemented. Although the plan said switching to gas could reduce dioxin emissions by up to 95 per cent, it also acknowledged that a full-scale switch had to take into account energy policy, economic considerations and the city's electricity needs. The proposal is understood to be a 'committed direction' of the government, although there is no clear timetable. It also proposes as a 'priority task' an investigation of the dioxin and furans content in coal-burning residues and recycled products containing the residues. Ash products - mixed with concrete or bricks - are widely used in construction projects. Ash is being stored in ash lagoons in Tuen Mun and on Lamma Island operated by the two power suppliers. But the one in Tuen Mun might need to be moved because the government wants to use the site for landfill expansion. Friends of the Earth environmental affairs manager Hahn Chu Hon-keung supported a review of the heavy reliance on coal. 'The dioxin emission from coal burning is one of the neglected areas in the electricity market reform and now it is time to deal with it. There is no excuse for the power companies to evade it,' he said. Mr Chu said he was worried that few studies had been done on ash products, and feared that dioxin residues could be released back into the environment when structures or roads were demolished. CLP Power said it was studying the implications of the convention. Hongkong Electric said: 'Dioxin emission in coal-fired generation process is negligible due to its high boiler combustion temperature.' Blueprint for cleaner living Measures being considered include: A law to regulate the import/export and use and production of the eight pesticides on the list of 12 chemicals targeted by the convention; Strengthen monitoring of the toxins in the atmosphere, soil, sea water and animals; Improve analysis of the level of the 12 toxins in the routine surveillance of food and drinking water; Consider drawing up an action level for food safety in terms of organic pollutants levels; More studies on toxic levels in breast milk and blood; Consider the use of cleaner fuel in power generation and vehicles; stop pumping untreated sewage into the harbour; waste incineration to minimise toxins in landfills.