BEIJING, Oct. 29 (Xinhuanet) -- With cold weather conditions setting in, a heavy blanket of smog has enveloped northern China. Beijing, Tianjin and Hebei province have issued air quality alerts as result.

Beijing has activated its blue alert for heavy air pollution. It is the very first time that the alert has been issued since the warning system was put in place last week. Blue is the first of four levels.

Mandatory factory and school closures and bans on cars entering the city are to be applied if the highest red alert is issued. All areas in Beijing have recorded heavy pollution readings, with the south of the city recording the worst levels yet. But conditions are expected to ease off with rains tonight.

Hebei province has issued a yellow alert for haze for the fourth day running. And the air quality index of its capital, Shijiazhuang reached 460; the highest level of pollution.

Tianjin also issued a yellow alert for haze, but the air quality is to ease with increased winds tonight.

(Source: CNTV.cn)