China's recent sandy weather had resulted in poor air quality in some regions, the Ministry of Environmental Protection said?in Beijing?Tuesday.

The recent sandy weather was comprised of three serious sandstorms from March 11 to 22, with the weather being at its worst from March 19 to 21,the ministry said.

Last Saturday, the affected area reached 1.4 million square kilometers, about 14.6 percent of China's land area.

According to the ministry, the sandy weather caused 23 cities including eastern Shanghai, Nanjing and Suzhou to become "gravely polluted" on Sunday.

The origin of the sand mainly came from southwestern Mongolia, Sino-Mongolian border and China's South Xinjiang Basin, said Tao Detian, a spokesman with the ministry.

"The influence of the sandy weather has extended to the middle and lower reaches of the Yangtze River, south of the Yangtze River and the southeast coastal area," he said.

Environmental experts said the sandy weather was mainly attributed to the rapid temperature rise in western China, rapid soil thawing compared with previous years, and recent frequent cold air activity.