China has started publishing hourly air-quality information for major cities across the country as the world's top source of greenhouse gas emissions tries to rein in its notorious pollution.

The levels of sulfur and nitrogen dioxide as well as particulate matter in 113 major cities will be updated every hour and published online under the new system launched Thursday by the China National Environmental Monitoring Centre.

The new system will "satisfy the people's right to know information about the environment," the centre was quoted by state media as saying.

It will "play a crucial role in air pollution prevention and control".

Beijing started publishing daily air quality reports a decade ago using information from more than 2,000 air-quality monitoring stations across the vast country, the official Xinhua news agency said.

China -- which this week admitted it is the world's biggest greenhouse gas emitter -- has some of the world's worst air pollution after rapid growth over the past 30 years triggered widespread environmental damage.

The US embassy in Beijing already runs an hourly air quality index for the city that is published on social networking site Twitter and was set up as an alternative to official Chinese data widely criticised as downplaying pollution levels.

The embassy's index caused a stir on Twitter last week when it described pollution levels in the capital as "crazy bad". The phrase was later deleted by the embassy.