A national environmental watchdog warns of severe air pollution in large areas of northern China including Beijing, Tianjin and Hebei province. Due to disadvantaged weather, the period from Friday, Oct 23, to Sunday, Oct 25 will see a big jump in air pollution.

Beijing has recently seen above average air quality scoring the second level in the six-tier rating system. As of Tuesday, the air quality was around 65 microgram per cubic meter.

Luo Yi, head of environmental monitoring department under the Ministry of Environmental Protection, says beginning Wednesday, the air quality will become worse. Light pollution will spread in major parts of the Beijing-Tianjin-Hebei region, and keep deteriorating to reach severe air pollution measures.

The western parts of Shandong province may see an increase in air pollution this week.

"The major pollutants in this round of smog covering the northern region will be PM2.5," Luo said.

The ministry adds that the disadvantaged weather conditions starting Wenesday will disperse the air pollutants, leaving smog in the air that may last for days.