BEIJING - Beijing launched carbon emissions trading on Thursday, making it China's third market for compulsory carbon trading.

An initial 490 companies, whose carbon emissions account for 40 percent of the city's total emissions, have been included in the scheme, according to the Beijing Municipal Commission of Development and Reform.

Under the trading program, companies which produce more than their fair share of emissions will be able to buy unused quotas on the market from companies that cause less pollution.

The market is based at the Beijing Environment Exchange. Five deals worth 40,800 tonnes in carbon quotas have been traded thus far at prices ranging from 50 to 51.25 yuan ($8.16-$8.36) per tonne.

On Tuesday, Shanghai launched its compulsory carbon trading market, the country's second such market, and south China's Shenzhen City started its market in June.

The National Development and Reform Commission, the nation's top economic planner, has also approved pilot carbon emissions trading schemes in Beijing, Tianjin, Chongqing, Hubei and Guangdong.

The country has pledged to reduce carbon dioxide emissions 40 to 45 percent per unit of GDP by 2020 compared with 2005 levels.