Most urban districts of Beijing and other parts of eastern and northern China on Monday suffered heavy fog and smog, reducing visibility in some areas to less than 50 meters. /VCG Photo

Beijing was engulfed in a thick blanket of smog, sending air pollution levels to "hazardous" according to the Beijing environmental protection monitoring center. A sandstorm is approaching towards China's northwestern region, as per weather forecast. /VCG Photo 

East China's Jiangsu Province was also swept by thick fog, with visibility of less than 200 meters in many areas. /VCG Photo

The Shandong provincial meteorological bureau has upgraded the alert for heavy fog on Monday morning from yellow to orange. The warning code has four colors, with red indicating maximum intensity, followed by orange, yellow and blue. /VCG Photo