When will the sandstorm end dyeing Shanghai's sky?
Sandstorms have been lingering in Shanghai since Tuesday.
Shanghai's dusty weather will improve slightly on Friday thanks to some rain, but the sky over the city will be shrouded again over the weekend, the local weather forecaster and air quality watchdog said on Thursday.
The city's air quality reading will improve to "well" on Friday, but the dust will return from Saturday amid rising temperatures, with air quality reading again plunging to polluted. The mercury will rise to 30 degrees Celsius early next week with sunny weather, according to the Shanghai Meteorological Bureau.
The sandstorms that have plagued nearly 40 percent of China's territory originated from south Mongolia and the Inner Mongolia Autonomous Region on April 9, overwhelming northeast, north and east China.
The dusty weather began hitting Shanghai on Tuesday night, dyeing the skyline yellow and sinking air quality readings to severely polluted.
Concentration of PM10 particles, the main pollutant, jumped to the highest level of 803 micrograms per cubic meter on Tuesday, when visibility was reduced to 2 kilometers in most areas.
Local residents grumbled that their faces were covered by a layer of dust whenever they went out.
Air pollution, once common in Shanghai, has become rare in recent years following the local government's strict curbs on auto emissions and discharges from factories, along with other air purification measures.
But the pollution has been affecting Shanghai for several days now, because an easterly airstream brought back part of the sandstorms that had already been blown to the sea, the Shanghai Environmental Monitoring Center noted.
"The sandstorm left and returned to Shanghai," a forecaster of the center said.
As a result, the city's air quality readings will hover around "well" and "slightly polluted" for the next few days, he added.
The National Meteorological Center renewed its blue sandstorm alert on Thursday morning, the lowest level in its four-tier system. Shanghai is still among a list of northwestern, northern and eastern cities and provinces to be affected.
Buildings are shrouded in sand and dust during a sandstorm in Beijing on Thursday.
Eight sandstorm weathers have swept China this year. During the dust storm this time, about 400 million people in 15 provinces, autonomous regions and cities have been affected.
Severe desertification in Mongolia in recent years has been blamed for the frequent sandstorms.
According to the Natural Environment and Tourism Ministry of Mongolia, 76.8 percent of the territory has suffered from desertification. The strong cyclone and cold front have pushed the sand into neighboring China.
Li Xinsheng, chief forecaster of the meteorological station in Shanxi Province, explained to Xinhua news agency that though shelterbelts have expanded in recent decades in north China to reduce near-surface wind speeds and stave off desertification, they can do little to stop the cross-border migration of dust in the upper air.
