Beijing city, on 2 October, issued its first yellow alert for air pollution in the second half of this year with Met department forecasting that smog will continue to engulf the Chinese capital till tomorrow.
The alert puts restrictions on work at construction sites, outdoor barbecues and straw burning by farmers. The reading of Air Quality Index (AQI) in Beijing was between 200 and 300 yesterday, meaning heavy pollution.
The smog began to envelop the capital and surrounding areas yesterday, just as a week of national holidays began.
The National Meteorological Center issued a yellow alert for smog that will be dispersed by a cold snap on Tuesday.
Wang Zifa, a researcher with the Institute of Atmospheric Physics of the Chinese Academy of Sciences, expects north China to face more bouts of smog in autumn and winter this year.
China has a four-tier colour-coded system for severe weather, with red being the most serious, followed by orange, yellow and blue.