The State Council, or China's cabinet, on Wednesday passed revised air quality standards which include an index for PM2.5, or "fine" particulate matter 2.5 microns or less in diameter.

The new standards include indices for the concentration of PM2.5 and ozone (O3) over a period of eight hours, according to a statement from the State Council issued after a meeting presided over by Premier Wen Jiabao.

However, the statement did not reveal the details of the two indices.

In 2012, the monitoring of PM2.5 and O3 will be conducted in four municipalities, 27 provincial capitals, as well as three key regions -- east China's Yangtze River Delta, south China's Pearl River Delta, and Beijing-Tianjin-Hebei area in the north, the statement said.

In 2013, the monitoring will be extended to 113 model cities on the state environmental protection list, and to all cities in 2015, the statement said.

(Xinhua News Agency February 29, 2012)