"[T]he emissions from power companies in Hong Kong are regarded as the main source of air pollution," Chief Executive Tsang said..."this standard will be complied with by the power companies and I will consider it in the context of the renewal of the scheme of control which will expire in 2008," Tsang said...The scheme of control is a contractual agreement between the Hong Kong government and the two local power companies -- CLP Holdings and Hong Kong Electric Holdings Ltd -- governing pricing and profitability...Hong Kong's worsening air pollution has become a growing cause of concern, affecting public health and even scaring foreign businesses away from the territory.