Tourists wear protective masks on the Bund in Shanghai yesterday as the city again choked on heavily polluted air. [Photo/Shanghai Daily]

The Shanghai Environmental Protection Bureau issued a yellow air pollution alert yesterday at 9:30pm. A yellow alert is triggered when the Air Quality Index is forecast to be between 201 and 300, or heavily polluted.

The Shanghai Meteorological Bureau also issued a yellow haze alert at 8:35pm yesterday for smog which is expected to last until today afternoon.

At 9pm, the air quality index was recorded at 215, or heavily polluted, with the concentration of PM2.5 reaching 165 micrograms per cubic meter.

The smog is expected to remain today when it could possibly become "severely polluted." It is likely to ease later tonight.

But a weak cold front on Thursday will likely bring the pollutants back.

The meteorological bureau said the persistent pollution in the city was mainly caused by two factors — the soaring pollutant concentration in north China and city’s firm weather.

How high the pollution level is depends on how dense the pollution is in northern China, the wind direction and the strength of wind. The concentration of pollutants can be cut by strong winds and rainfalls.

Meanwhile, the soggy weather is expected to last until Wednesday due to an active short wave trough that will likely bring cooler temperatures and more pollution, forecasters said.

The rains will give way to cloudy skies on Thursday when a cold front moves in, bringing in strong northerly winds and pushing the mercury down to single digits.

Today, it will be cloudy with some drizzles followed by a slight dip in temperature. A high of 13 degrees Celsius and a low of 10 degrees are expected.

The rains will increase tomorrow before tapering off on Wednesday. From Tuesday to Thursday, the temperature will be between 10 and 6 degrees.

Go to Forum >>0 Comment(s)