Greenpeace wants the government to impose a legal cap on carbon dioxide emissions from power plants after a survey found more than 80 per cent of people agreed with the move. Of the 514 people polled, 70 per cent were concerned with the effects of global warming on Hong Kong. Activist Frances Yeung Hoi-shan said the government should regulate emissions from power plants. The group urged electricity companies to cut their emissions by 15 per cent from 2006 levels by 2020. Research by the Environmental Protection Department shows power plants account for more than 60 per cent of the city's carbon dioxide emissions, which had increased 14 per cent in the past decade. On Thursday, the Legislative Council will discuss an amendment to the Air Pollution Control Ordinance to regulate emissions from power plants, including sulfur dioxide and nitrogen oxide. However, emissions of carbon dioxide will not be regulated, according to government proposals. 'The government refused to regulate power plants' carbon dioxide emissions, saying that it would increase electricity costs and bring technical problems,' Ms Yeung said. Meanwhile, the Democratic Party has called for the government and bus companies to speed up measures to reduce air pollution. Party legislator Sin Chung-kai said there was no government policy to regulate the phasing out of old diesel buses and state subsidies were needed. Kowloon Motor Bus, the city's largest bus company with 4,000 buses, plans to phase out its dirtiest vehicles in six years, including more than 500 buses predating Euro emission standards.