Residents in parts of north China's Inner Mongolia Autonomous Region were again forced to wear glasses and face masks Wednesday as another sandstorm hit.

The Xilin Gol League and Xing'an League, in central Inner Mongolia, were main areas struck by the sandstorm, according to local meteorological authorities.

In Xilin Gol, some women donned plastic bags to keep their hair in place as the strong winds blew yellow sand across the area. Visibility had dropped to less than 100 meters by 9 a.m..

The sandstorm was the third to hit the area, 600 km from Beijing, since March 11.

Sandstorms frequently affect the area as most of the Xilin Gol grasslands have been damaged by population growth and over-grazing.

Rising temperatures that melted ice in the soil and created dusty conditions after a severe winter have been blamed for this year's frequent sandstorms.

In Xing'an League, some flights were delayed by at least two and a half hours due to the bad weather. Visibility was reduced to less than 300 meters in some areas.

The Alxa League, in the westernmost part of Inner Mongolia, saw strong winds and dusty weather Tuesday and Wednesday, but not as strong as that in the other two leagues.

Although the Alxa League has been considered one of the major sources of sandstorms in China, meteorologists have pointed out that the league was not the source of the sandstorms this year.

"The sandstorm that hit the central parts of Inner Mongolia this time originated again in Mongolia, instead of the Alxa League. That is a result of the eastward movement of a Mongolian cyclone," said Zhang Huiyuan, a senior engineer with the Meteorological Bureau of the Alxa League.

"Actually, sandstorms originating in the league itself have been rare since 2006," he said.

"Years of efforts to improve ecological environment, such as tree planting and water diversion, have played a role in staving off sandstorms," he said.

But Inner Mongolia and other parts of China would see more sand and dust in the air over the next 10 days, said Zheng Jiangping, a disaster-relief official with the China Meteorological Administration.

China suffered six sandstorms in March, with the worst affecting 21 provinces and regions from March 19 to 21.