Fear of dust is called Koniophobia.
Not to be confused with amathophobia, which is the fear of sand.
People who have a fear of dust sometimes have OCD or Obsessive Compulsive Disorder. It could also mean you’re just very clean or a neat freak.
Fear of sand could often result after your older brother buries you at the beach, or if you get sand in your bathing suit and the grains work their way up special places and you get a rash that lasts for days. Not that we would know.