Heavy smog shrouds buildings on January 1, 2017 in Beijing, China.

Choking smog continued to blanket a vast area of the mainland, disrupting schools and traffic on the second day of the new year.

Nine provinces and municipalities in the northern and central regions, including the area comprising Beijing, Tianjin and Hebei as well as Shan­dong, Shaanxi and Henan provinces, were engulfed by heavy air pollution.