I also built one, and I attached charcoal filters to it, which has significantly reduce the amount of dust in my house, and the air generally smells not at all.

The previous owners of my house were dog owners, so if I don’t run it for a while, then there’s like a hint of dog odor that even replacing all of the carpet and flooring in the entire house and running an ozone machine on workdays for a week has not gotten rid of.

But as long as the fan is running, that odor is taken care of.