Today is quite bad with the yellow sand dust.
→  오늘은 황사로 너무안좋아.

[예문]
A: How are you doing?
  잘지내?

B: Thanks for your concern..
  관심가져줘서 고마워.

  Yeah, today is quite bad with the yellow sand dust from China..
  근데,오늘 중국에서오는 황사로 안좋아.

A You should take a mask.
  마스크 꼭해.

B:It's really terrible in spring season.
  진짜 봄에는 황사가 너무싫어.