Yesterday, when I was in downtown of Tokyo, haze (dust storm) was coming suddenly. I bought face masks quickly to prevent myself from dusts. It cost 200 yen ($2.11 €1.60) for 7 pieces.
When that haze was coming, most of us including my son thought
"Chinese yellow sand storm is coming." (http://en.wikipedia.org/wiki/Asian_Dust)
Huge amount of yellow sands are carried by wind from China's dry land. It strikes Japan every year.
If you want to know something, ask me please.
