A few years ago, during my first stint in Japan, I heard about this phenomenon and experienced it. I have some photos somewhere of Hamamatsu with a strange yellow sky that looks more like Mars than Japan. And here we go again: Yellow sand, Chinese pollutants wreak havoc | The Japan Times.
Sunday, the sky over Shizuoka prefecture became a pale yellow, which persisted throughout the morning before giving way to more ordinary-seeming gray clouds. I stayed indoors all day. I'm experiencing the worst seasonal allergies of my life-- the pollen counts here in Japan are off the charts-- and I didn't want to exacerbate my breathing problems with fine grit and pollutants. I still spent the day battling a tremendous sinus headache and feeling generally ill. This may not have anything to do with the international pollutants or even with the local cedar pollen.
All I know is, the air lately is not my friend. I'm taking prescription allergy pills and managing to hold things together, but just barely.
On the other hand, today is sunny and very pretty to look at. Sunlight on bare tree limbs and shadows, street lights glittering. The weather's turning warmer and spring has winter on the run. If I can survive the pollen and sand storms I should be fine.