Tourists in mask visit Wanchun Pavilion in Jingshan Park in Beijing, capital of China, May 4, 2017. A sandstorm swept over much of north China including Beijing on Thursday, turning the sky yellow and obscuring visibility. The city's meteorological center issued a blue alert for sandstorms Thursday morning, forecasting winds to carry sand and dust across the capital. (Xinhua/Shen Bohan)
