SHANGHAI'S air quality is expected to improve today after the city experienced its dirtiest day since this summer yesterday. However, blue skies will still be elusive despite a sunny forecast by the weather bureau.
The city's PM2.5 readings, of airborne particles smaller than 2.5 micrometers, hit a seasonal high of 296.2 micrograms per cubic meter before 3pm yesterday under the influence of a weak cold front from the north, which reached the city on Sunday night, according to the Shanghai Environmental Monitoring Center.
The center had forecast Shanghai's air quality to be good yesterday.
The PM2.5 index remained below 40 micrograms per cubic meter from Sunday afternoon until 8am yesterday morning. But later it jumped quickly due to the haze and in some areas the figure had reached over 300 micrograms per cubic meter in the early afternoon.
The average PM2.5 readings for the last 24 hours was 77.3 micrograms per cubic meter. The nation's standard for PM2.5 in the latest 24 hours was 75 micrograms per cubic meter. So far, there is no limit on the hourly density of PM2.5.
The air quality was much improved later in the afternoon when the wind got stronger with the cold front. The PM2.5 index dropped to 64.9 micrograms per cubic meter by 4pm and the air was clear.
Yesterday's rapid rise in pollutants was mainly due to rising humidity since Sunday night as well as the pollutants brought by the cold front from the north, the center said.
"Though the average level for the last 24 hours was not so high, the hourly reading was alarming and we issued a warning to local residents in the afternoon, urging those with weak immunity and those suffering from heart and respiratory diseases to stay indoors," said Lin Chenyuan, a forecaster with the monitoring center. "The air quality will be between good and slightly polluted tomorrow (today)."
Meanwhile, the sky should be clear today and visibility better, according to the Shanghai Meteorological Bureau.
Temperatures in the mornings should be low today and tomorrow due to the cold front, going as low as 15 degrees Celsius in urban areas and even lower in the suburbs. Today is forecast to be sunny to cloudy with the mercury ranging from 15 to 22 degrees. The sky should turn cloudy and overcast again tomorrow and the high should climb to 24.
"More clouds are forecast from Wednesday and drizzles should occur frequently later in the week because of the rise in warm and wet air currents," said Zhang Ruiyi, a chief service officer of the meteorological bureau. "Temperatures should rise gradually toward the weekend before another cold front arrives."
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