Beijing and other parts of northern China were stung by hazardous air pollution levels Thursday as strong winds blew a sandstorm through the region.
Air in the capital turned a yellowish hue as sand from China's arid northwest blew in, turning the sky into a noxious soup of smog and dust.
At 6 a.m. local time, the U.S. Embassy's air quality index showed a reading of 516 for particles less than 2.5 micrometers in diameter. Known as PM2.5, such particles are considered particularly dangerous because they can lodge deeply in the lungs. On the American air pollution index, the air at that time and throughout much of the morning was classified as "beyond index."