City on alert for possible heavy air pollution
A yellow alert for possible heavy pollution on Tuesday morning was issued on Monday.
It was triggered at 3pm when the air quality index was recorded at 122, 22 points higher than the safety standard and reaching the lightly polluted level.
Officials expect pollution to rise on Monday night to become moderately polluted.
Due to cold air flowing into the city, carrying pollutants from northern China, pollution is likely to remain moderate but may worsen to heavily polluted for a short time on Tuesday morning.
Commuters are being advised to wear a mask during the morning peak period while children and the elderly should remain indoors.
The pollutants will linger in the city during the day but will be blown away as the wind gathers in strength.
The smog will disperse during the night and clean air will return on Wednesday though it will be cloudy with rain.
The rain will weaken to a drizzle late on Thursday and Saturday will be drying before the drizzle returns for a short time on Sunday.
Temperatures will range from 4 to 10 degrees Celsius this week.