BEIJING, Oct. 7 (Xinhua) -- Cold air and gales are expected to sweep Beijing in the coming 24 hours and clear the heavy smog that has blanketed the Chinese capital for three days.
Beijing's weather bureau has forecast gales to sweep at about 50 km per hour on Wednesday night and throughout Thursday.
It said the strong wind will bring down the high temperature to 19 degrees Celsius on Thursday, compared with Wednesday's 25 degrees Celsius.
Thanks to the gales, Beijing's sky will be clear and blue for three days from Thursday to Saturday, according to the weather report.
Beijing was overcast with smog from Monday to Wednesday.
The average density of PM 2.5, airborne particles measuring less than 2.5 microns, exceeded 313 micrograms per cubic meter in the six urban districts at 2 p.m. Wednesday.
The situation was slightly better in the outer districts, where PM 2.5 density ranged from 230 to 300 micrograms per cubic meter.
The city's emergency management headquarters said the smog was caused by higher humidity in the air, absence of wind, and the burning of stalks by farmers in the neighboring provinces.
Beijing's environmental protection bureau said air pollution was most likely to worsen in fall and winter.
Its analysis of air quality data over the past decade shows an average 23 days in the fourth quarter were heavily polluted, including seven days in October and eight days in November and December respectively.
"Smoke from the burning of stalks and coal, coupled with unfavorable weather conditions, often worsen pollution," said Zhang Dawei, head of Beijing environment monitoring center.