Sand, dust blown to northern region

The northern part of Beijing and several provincial-level regions were shrouded in dust on Tuesday after sand and dust from a storm that was caused by cold air and strong winds in the Inner Mongolia autonomous region spread across much of northern China, according to the National Meteorological Center.

The center issued a sand and dust storm blue warning on Tuesday－the lowest in the three-level alert system, in which orange is highest and yellow second-highest.

Northern Beijing, most parts of Shanxi, Shaanxi, Hebei and Henan provinces, and the southern part of the Xinjiang Uygur autonomous region also experienced sand and dust conditions.

The center warned of impacts on the environment, health and transportation and the risk of forest fires.

The meteorological service of the Inner Mongolia autonomous region said that the sand and dust storm first hit western areas of the region on Monday, reducing visibility in most places to 1,000 meters.

A video on the website of Beijing News showed a car trapped on a road on Monday amid very high winds and heavy dust in Alshaa League in the western part of the region.

On March 3 and 4, the year's first bout of dust and sand conditions hit North and Northeast China, bringing severe air pollution, the meteorological center said.

Wu Yanmei, a bank clerk in Beijing who rides a scooter from home to work, recalled the sand and dust causing her trouble during her commute earlier this month.

"I couldn't see the road clearly and was afraid of being blown down from my scooter by the heavy wind on that sandy day earlier in March. My face was dirty and covered with dust after I rode all the way to work," she said.

"Although compared with last March, the sand and dust weather this year is milder. But I still take precautions by wearing a face mask."

Rao Xiaoqin, the meteorological center's chief forecaster, said on Tuesday that the sand and dust storm－which caused concentrations of more than 420 micrograms of PM10 per cubic meter in Shaanxi, Henan and Hebei provinces－was expected to subside on Wednesday after rains that were forecast for Tuesday night. PM10 refers to inhalable particulate matter that is 10 micrometers in diameter or smaller.

Such a PM10 reading signifies severe air pollution, "but the rain that is forecast for these areas on Tuesday night should clear the dirt", Rao said.

She added that strong winds caused by cold air in the source areas of sand, including Mongolia and the Inner Mongolia autonomous region, transported the sand southward.

However, she said fewer than normal sand and dust weather episodes are expected this spring, because precipitation in January and February created conditions that are unfavorable for sandstorm formation in the source areas.

Last year, China saw the strongest sand and dust storm in nearly a decade, from March 13 to 18. The storm affected 19 provincial-level areas, leading to the suspension of school classes and cancellation of flights.

Sand and dust storms are common meteorological hazards in arid and semiarid regions. They are usually caused by increased wind speed over a wide area. Each year, around 2 billion metric tons of dust enter the atmosphere, the World Meteorological Organization said.

From 1981 to 2010, Beijing had an annual average of 2.4 days of sand and dust storms in March. The longest sandstorm so far this century occurred in 2001 and lasted nine days, the capital's meteorological observatory said.