Choking smog over eastern provinces spreads into Beijing

The massive smog cloud choking the eastern provinces since midweek expanded northwards to Beijing yesterday.

The air quality index in the capital was as high as 356 at 9pm, ending a week-long streak of blue-sky days. Anything worse than 300 is considered "severe", the highest rating on the six-level rating system.

Shanghai residents saw air pollution levels ease slightly.

The pollution-monitoring station atop the US embassy in Chaoyang district showed PM2.5 levels - potentially harmful particles less than 2.5 microns in size - of 473 micrograms per cubic metre at 9pm. The World Health Organisation's safe limit for PM2.5 is 25 mcg. The situation was even worse in the surrounding province of Hebei . The AQI in the provincial capital, Shijiazhuang , hit the top of the 500-point air quality index yesterday evening.

The National Meteorological Centre maintained the "orange" smog alert it issued nationwide on Friday.

Serious pollution was expected to continue in Anhui , Beijing, Hebei, Jiangsu , Tianjin and Zhejiang until this afternoon.

In Nanjing , which has been the centre of the current smog episode, the air quality index continued to hover around 300. Schools in the Jiangsu provincial capital have been closed since Wednesday to protect children from the potentially hazardous air.