Winds to Taper Pollution as Week Grows Warmer

A resident takes pictures of magnolia blooms on March 5 at People's Avenue. [Shanghai Daily]

Shanghai was moderately polluted yesterday and two alerts were issued as the primary pollutant, tiny PM2.5 particles, remained at around 160 micrograms per cubic meter the entire day.

Today's air quality will be better but not good enough for people to see a blue sky, as meteorological conditions won't improve greatly, forecasters said.

Weather conditions led pollutants to accumulate from Monday night and at 8:55 AM yesterday, the Shanghai Meteorological Bureau issued a yellow haze alert, lowest of the three-scale system, warning of moderate haze and encouraging locals who go out to wear masks.

At 9:00 AM, the Shanghai Environmental Monitoring Center issued a pollution alert as PM2.5 reached 159.8 micrograms per cubic meter. Officials reminded people with respiratory and heart diseases, the elderly and children to stay indoors.

The haze alert was lifted at 3:32 PM yesterday as conditions started to improve, officials said.

But the air quality index climbed steadily yesterday as pollutants trapped by a thermal inversion and slack winds reached 196 at 12pm, four point from the range of serious pollution. While overall pollutants stayed high, one component, PM2.5 particles, began dropping as of 2pm and fell below 120 micrograms per cubic meter by midnight. China's national standard requires the PM2.5 density be kept below a daily average of 75 micrograms per cubic meter.

Today's wind "should be mostly southerly and stronger," which should take away the heaviest haze, said Zhu Jiehua, a chief service officer of the weather bureau.

Experts said the dirtiest air usually is found from the ground to the third floor of buildings, as pollutants like PM2.5 and PM10 usually accumulate below 10 meters, correcting erroneous online posts by netizens.

Today is forecast to be partly cloudy with temperatures ranging from a low of 9 degrees Celsius to a high of 21.

Tomorrow should be overcast with a high of 22 degrees.

On Friday, the high is expected to reach 24 degrees Celsius.