A pedestrian walks through a severe sandstorm that hits Beijing on Monday. [China Daily]

Another eight to 10 sandstorms are expected to hit North China in April and May as a result of the frequent cold spells, meteorologists predicted on Monday.

The forecast came as sandstorms whipped across the country, shrouding cities in a cloud of sand, with winds carrying the dirt as far as Hong Kong and Taiwan.

"The warm weather in March dries the sand, while the frequent cold spells in spring bring wind. Dry sand and wind trigger sandstorms," Zhang Peiqun, chief forecaster from the National Meteorological Center (NMC) told China Daily. The NMC lowered its alert level from yellow, the third highest, to blue, the forth highest, on Monday. But this does not mean the end of the sandstorms that have hit most parts of North China, Zhang said.

"A new round of cold spells will bring more sandstorms to North China. That's the way it's been in the spring every year since 2000," Zhang said.

Beijing witnessed its second sandstorm on Monday, four days after the first one over the weekend affected some 270 million people in 16 provinces, covering 2 million sq km across the country, meteorological experts said.

"The sandstorm from Mongolia arrived in Beijing on Monday morning and is expected to weaken by the evening," Zhang Mingying, a senior engineer with the Beijing Meteorological Station, told Xinhua News Agency.

He said the sandstorm, borne by strong winds, had swept over North China's Inner Mongolia autonomous region, and Shanxi and Hebei provinces.

Experts said the center of the sandstorm is located in the Inner Mongolia and Ningxia Hui autonomous regions.

The dust floating in the air due to the sandstorms turned the sky dark yellow in some parts of South China.

"The coastal areas seldom have haze. If the recent haze continues, it might develop into a sandstorm," Liu Ming, deputy director of Fujian's meteorological bureau told Chinanews.com on Monday.

China's Central Meteorological Station urged people to close doors and windows, and to cover their faces with masks or scarves when outdoors. Sensitive electronic and mechanical equipment should also be sealed off, the station said.

China Central Television told viewers to clean out their noses with salt water and to remove grit from ears with cotton swabs dipped in alcohol.

State television's noon newscast showed the tourist city of Hangzhou on the eastern coast, where graceful bridges and waterside pagodas were hidden in a mix of sand and other pollution. In Beijing, residents and tourists scurried along sidewalks with their faces covered to minimize exposure to the pollution.

The US Embassy in Beijing warned that particles in the air made conditions "hazardous" and the air quality was later upgraded to "very unhealthy".

Duan Li, a spokeswoman for the Beijing Meteorological Station, said conditions in the city seemed more severe because a sandstorm on Saturday deposited grit on rooftops, sidewalks and trees. The winds on Monday carried even more sand, stirring up what was already there.

A massive sandstorm hit Beijing in 2006, when winds dumped about 300,000 tons of sand in the capital.

Sandstorms have been a big problem in North China after years of overgrazing, deforestation, urbanization and drought, with deserts making up about 16 percent of the country.

Authorities have invested nearly 4 billion yuan ($588 million) in a wind and sandstorm source control project in Beijing and Tianjin from 2000 to 2009 to prevent sandstorms.

The average number of sandstorms over the past decade is less than nine times every year. About 80 percent of the sandstorms annually happen in spring.

Xinhua and Reuters contributed to the story