Why does every building get dusty inside?

Question

Why does every building get dusty inside?

In: Earth Science

Answer 1

Because the people inside lose a lot of hair and old skin, dirt from outside gets blown in by the wind and animals (flies mostly, but also bigger ones) bring dirt inside.

Dust is a mixture of all the stuff flying around and settting somewhere and is, at least i our homes, mostly made up of dead skin and hair.