5月31日，在美國加利福尼亞州洛杉磯，游客在瞭望平臺觀望被霧霾籠罩的城市。新華社/法新

Tourists at the Griffith Observatory observation deck look out at the Los Angeles city skyline as heavy smog shrouds the city in California on May 31, 2015. AFP PHOTO/ MARK RALSTON