A cyclist covers her face with a mask to protect her from floating dust in Yinchuan, capital of northwest China's Ningxia Hui Autonomous Region, May 13, 2013. Floating dust hit Yinchuan on Monday. Monitoring data released by Yinchuan Environmental Protection Bureau shows that the reading for PM2.5, or airborne particles measuring less than 2.5 micrometers in diameter, has reached 107 micrograms per cubic meter at Ning’an Street as of 12:00 a.m. on Monday. [Photo/Xinhua]