A power company run by a son of former premier Li Peng is among the top five firms on a list of the worst air polluters in Beijing. It is the first time authorities have adopted a name-and-shame approach to try to improve the capital's chronic air pollution. The pollution-control office under the municipal Environmental Protection Bureau has released a list of 28 companies that it says produce a total of 78,000 tonnes of sulfur dioxide and 13,000 tonnes of particulate matter each year. It said this accounted for 68 per cent of the city's sulfur dioxide emissions and 44 per cent of particulates. Five coal-powered electricity-generating companies were cited as the worst offenders, including the Beijing subsidiary of Huaneng Power International, which is the mainland's largest independent power producer and is run by Li Xiaopeng . The five power companies emitted 60 per cent of the city's sulfur dioxide and 26 per cent of the particulates, the pollution office said. Apart from emitting pollutants, companies have also been put on the list for failing to introduce environmental-protection measures and for being located in environmentally sensitive zones. All companies on the list not involved in power generation had been told to reduce emissions by the end of the year or face punishment, officials said, without stating what the penalties would be. But they said that the power companies, by far the worst culprits, would be given more time to implement reforms because the nature of their business made it more difficult to reduce emissions. Officials would not say how long the power companies would be given. Du Shaozhong, of the Beijing Environmental Protection Bureau, said that if the 28 companies on the list adhered to city regulations, annual levels of sulfur dioxide would drop by 50,000 tonnes. The amount of particulate matter could be expected to fall by 4,000 tonnes. Mr Du said the maximum penalty of 100,000 yuan allowed under the air pollution law was not an adequate deterrent. It would cost the companies much more than 100,000 yuan to install environmental-protection equipment. An official said the city government would add more names to the list of serious polluters later in the year.