The sandstorms, which have swept across northern China, have affected the air quality in nearly 50 percent of the country's major cities, affecting roughly 100 million people, China's environmental watchdog announced on Friday.

The State Environmental Protection Administration (SEPA) said that as of April 19, 55 of the 113 cities monitored in China had seen fewer clean days from a year earlier, and 10 cities in northern China including Beijing and Yinchuan have reported a decrease of over 10 blue sky days.

Sandy weather came earlier and more frequently in China this year, SEPA said, adding that sand blanketed 14 provinces, regions and municipalities in China, such as Beijing and Tianjian, covering a total area of nearly 4 million square kilometers and quadrupling the area a year earlier.

China has witnessed eight serious bouts of dusty weather so far this year, with three major sandstorms.

During the latest sandstorm from April 16 to 18, around 330,000 tons of sand fell on Beijing.

The frequent sandstorms this year can be attributed to high temperatures, prolonged drought and frequent cold air, according to SEPA.

Forecasts show northern China will experience two sand storms in the next ten days, exerting their force from April 21 to 22 and around April 27.

(Xinhua News Agency April 22, 2006)