Depending upon the context of your dream dust in dream may symbolize wealth, chaos, uprising, catastrophe or divine punishment.
Guiding Dream Interpretations
To dream that your belongings are dusty then it may be a sign of getting riches.
To dream that dust is suspended in some particular area or a zone between earth and sky then the dream signifies that something done secretly will be revealed or declassified.
To dream that your face is dusty then it is a sign of grief and sorrows.