The Chinese capital Beijing was shrouded in thick brown dust on Monday due to strong winds blowing in from the Gobi desert and parts of northwestern China, in what the weather bureau has called the biggest sandstorm in a decade.

On Monday morning, the China Meteorological Administration announced a yellow alert, saying sandstorms had spread from Inner Mongolia into the provinces of Gansu, Shanxi and Hebei, which surround Beijing.

The tops of towerblocks in central Beijing were barely visible today, and commuters could be seen wearing improvised headwear to protect their faces and hair.

“It looks like the end of the world,” said 25-year-old Flora Zou, a Beijing resident who works in the fashion sector. “In this kind of weather I really, really don’t want to be outside.”

China’s state news agency Xinhua reported that heavy sandstorms also hit neighboring Mongolia, with more than 341 people reported missing.

Flights have been grounded out of Hohhot, capital of China’s Inner Mongolia.

Around a fifth of the incoming and outbound flights at Beijing Capital International Airport and Beijing Daxing International Airport had been cancelled as of noon (0400 GMT), more than usual during the sandstorm season, according to aviation data provider Variflight.

The sandstorms were expected to shift south towards the Yangtze River delta and should clear by Wednesday or Thursday, the environment ministry said.

Beijing faces regular sandstorms in March and April due to its proximity to the massive Gobi desert as well as deforestation and soil erosion throughout northern China.

China has been trying to reforest and restore the ecology of the region to limit how much sand is blown into the capital.

Beijing has planted a “great green wall” of trees to trap incoming dust, and has also tried to create air corridors that channel the wind and allow sand and other pollutants to pass through more quickly.

Last year, the environment ministry said the situation had improved, with the first storms now arriving much later in the year and not lasting as long as they did a decade ago.

Beijing and surrounding regions have suffered from high levels of pollution in recent weeks, with the city shrouded in smog during the national session of parliament which kicked off on March 5.

“It’s hard to claim we are moving forward when you can’t see what’s in front,” Li Shuo, climate advisor with Greenpeace in Beijing, wrote on Twitter on Monday.