The mainland's first sandstorms of the season are causing tension beyond China's borders by spewing harmful 'yellow dust' as far as Japan and forcing school closures in South Korea.
The annual phenomenon, which China's neighbours claim has been growing worse in recent years, has sparked calls for Beijing to share information and boost transparency to help other countries prepare.
South Korea closed schools yesterday while factories producing memory chips stepped up safeguards, as the choking cloud of sand and toxic dust covered much of the Korean Peninsula.
Experts say the dust picks up heavy metals and carcinogens as it passes over Chinese industrial regions, before hitting North and South Korea and Japan.
In Japan, the government urged drivers and train operators to be on alert because the sandstorms had reduced visibility.
The China Meteorological Administration warned of more sandstorms and dust for northern China, including Inner Mongolia and Hebei, from tomorrow until next week, Xinhua said.