China's biggest sandstorm in a decade has covered Beijing in a thick blanket of brown dust and grounded more than 400 flights.
The China Meteorological Administration announced a yellow alert on Monday morning, as the storms, powered by heavy winds blowing in from the Gobi Desert and parts of northwestern China, covered the capital in a thick, orange-brown dust.
The agency said the storms, the worst in at least 10 years, spread from Inner Mongolia into the provinces of Gansu, Shanxi and Hebei, which surround Beijing.
Neighbouring Mongolia was also hit by heavy sandstorms, with at least 341 people reported missing, according to China's state news agency Xinhua.
Hundreds of flights out of Beijing's two main airports were cancelled.
The capital's official air quality reached a maximum level of 500 on Monday morning, the Beijing Municipal Environmental Monitoring Centre said.
Rush hour commuters choked as floating particles, known as PM10, rose beyond 8,000 micrograms per cubic metre in some districts,160 times the level of 50 recommended by the World Health Organisation (WHO).
