China today issued a yellow alert for heavy smog that will shroud the country's northern and eastern regions, including Beijing and Shanghai, till tomorrow.
The National Meteorological Center advised people in these areas to stay indoors and wear masks when going out.
Smog will blanket parts of Beijing, Tianjin, Hebei, Henan, Shandong, Jiangsu and Shanghai from tonight till tomorrow night, the NMC forecast.
China has a four-tier warning system, with red as the most severe, followed by orange, yellow and blue.
Haze has repeatedly hit China, especially the north, this winter, although the 2015 average PM2.5 density in and around Beijing dropped 10.4 per cent from 2014.
China's Minister of Environmental Protection Chen Jining demanded tough and targeted measures to ensure sound air quality in the first quarter of 2016.
