A strong sandstorm sweeps Dunhuang city, Northwest China's Gansu province, March 31, 2015. The visibility in the downtown area was reduced to less than 50 meters while Mogao Grottoes, a UNESCO world heritage site in Dunhuang, was also closed to visitors. The Mogao Grottoes have gained global recognition for their huge collection of Buddhist artwork, boasting more than 2,000 colored sculptures and 45,000 square meters of frescoes in 735 caves carved along a cliff. (Photo: China News Service/Zhong Xin)
