Answer:
Dust is a mixture of different things, that is the reason that can posses charge.
Explanation:
Dust can be formed by small particles, smaller than 500 micrometers, but the nature can be so different from one place to another.
If is inside a house, maybe is a mixture of skin (that could contain lipids), human or pet hair (that posses some radical organic groups), minerals particles (that can have in the outside part some ionic compounds easily to change to an ion alone.
If the dust is in a yard, maybe is a mixture of grass or leaves (that they are formed by some cells parts). If there are just some part of the organelles like some parts of the membrane, the ionic particles can reach to an ionic charge.
