Sandstorms whipped across a wide swath of China on Monday, forcing residents to don masks and scarves to protect themselves from the unhealthy grit.
It was the latest sign of the effects of desertification - overgrazing, deforestation, urban sprawl and drought have expanded deserts in the country's north and west.
The shifting sands have gradually encroached onto populated areas and worsened the sand storms that strike cities, particularly in the spring.
Winds blowing from the northwest were sweeping sand from the Xinjiang and Ningxia regions, as well as Gansu and Inner Mongolia provinces across China's arid north. The sand and dust were even carried to parts of southern China.
The noon newscast on state television showed the tourist city of Hangzhou on the eastern coast, where graceful bridges and waterside pagodas were hidden in a mix of sand and other pollution.
In Taiwan, an island 100 miles (160 kilometers) away from the Chinese mainland, drivers complained their cars were covered in a layer of black soot in just 10 minutes.
The Central Meteorological Station urged people to close doors and windows, and cover their faces with masks or scarves when going outside. Sensitive electronic and mechanical equipment should be sealed off, the station said in a warning posted Monday on its Web site.
China Central Television told viewers to clean out their noses with salt water and remove grit from ears with cotton swabs dipped in alcohol.
It was the second sandstorm to hit Beijing in three days and skyscrapers in the capital were shrouded in a grayish mix of sand, dust and pollution.
Residents scurried along sidewalks trying to avoid breathing in the fine particles that can cause chest discomfort and respiratory problems even in healthy people.
The US Embassy in Beijing warned that particulate matter in the air made conditions "hazardous," though high winds dispersed some of the pollution and the air quality was later upgraded to "very unhealthy."
Duan Li, a spokeswoman for the Beijing Meteorological Station, said conditions in the city seemed more severe because a sandstorm on Saturday deposited grit on rooftops, sidewalks and trees. The winds Monday carried in even more sand and stirred up what was already there.
Conditions were expected to improve by Monday night, with winds blowing the sand toward the southeast.
The worst recent sandstorm to hit Beijing was in 2006, when about 300,000 tons of sand were dumped on the capital.