The Hexi Corridor or Gansu Corridor, a long, narrow passage stretching for some 1,000 kilometers (about 600 miles) in northwestern China, was hit by sandstorms sweeping from west to east. On the evening of Nov. 26, Jiuquan, Jiayuguan, Zhangye, Wuwei and other cities issued yellow warnings for sandstorms.
The air quality index in many major cities reached more than twice of the threshold set for monitoring air pollution. Air pollution in one city exceeded the limit by three times.
In China, sandstorm warnings are divided into three levels, yellow, orange and red, as determined by the China Meteorological Administration. The yellow sandstorm warning is defined as visibility less than 1,000 meters (3,280 feet), as well as possibility of sandstorms within 12 hours.
A resident from Zhangye City located around the middle section of the Hexi Corridor said that it was still sunny and clear on the morning of Nov. 25, but starting around 4:00 p.m., sand and dust driven by a strong wind formed a nearly 100-meter-high (328 feet) storm that approached the city and soon engulfed it.
Videos in Zhengye taken around 4:00 p.m. in the report show sandy wind rolling to the city from a distance and gradually swallowing it. As the wind and sand slowed, it left a dim yellowish hue in the sky.
People in many places in the Hexi Corridor had difficulties breathing freely due to the sandstorm, according to the state-run China News.
The air quality index of dozens of cities exceeded 500, the highest value of the air quality index set for monitoring air pollution, at 11 o’clock on Nov. 26. The density of PM10 (atmospheric particulate matter exceeding 10 nanometers in diameter) per hour reached more than 1,000 per cubic meter (35.3 cubic feet) in some areas, including Lanzhou, the capital of Gansu province, which experienced 1,008 micrograms. PM10 in Qinghai’s provincial capital of Xining, the capital of Qinghai province, reached 1,279 micrograms per cubic meter. Jinchang City reached 1,212 micrograms per cubic meter, and Wuwei City reached 1,708 micrograms per cubic meter, exceeding the monitoring threshold by three times, according to the China National Environmental Monitoring Center.
PM10 is particulate matter or particle pollution, a mixture of airborne solids and liquid droplets equal to 10 micrometers in diameter. The particles can lodge themselves in the lungs and cause serious respiratory and other health problems.