Large parts of north and central China shrouded in smog

Heavy smog has shrouded large parts of northern and central China, and is predicted to remain for days.

The air pollution index has reached health threatening levels in parts of Beijing, Tianjin, Hebei, Henan, Shanxi, Shaanxi and Shandong, forcing authorities to issue an alert for air pollution.

In Beijing, dozens of highways have been temporarily closed due to low visibility. School students have been asked to avoid outdoor activities and reduce physical exercise. Residents, especially elderly and children, were advised to take protective measures.

Since Wednesday, PM2.5 levels in several major cities in Hebei Province have been over 400, a hazardous level. Many residents are using basic precautions such as wearing a mask or limiting outdoor activities.

The weather authorities say a cold front is expected to arrive Saturday night and disperse the smog.