Mid Lease Smoking Ban Allowed?

[Dave Kush]

Can I ban smoking in the building, including common areas, mid-lease?

I bought a duplex and inherited tenants/leases last year.  One unit is rented by smokers (they use common laundry area), and the other unit recently became vacant.  We are concerned that the smoking/smell will turn off prospects as well as the extra cost of cleaning up areas after smokers move out.

The building is in Illinois.  Smokers are not considered a "protected class" (ie: race/gender/age/etc).

The lease the tenant signed prior to us acquiring the property says nothing about smoking either way.  

I know I'm within my rights to not allow smoking within the building, especially if there's a new tenant, but not sure if I am able to do that mid lease.

Does anybody have any experience with this?  Are there general rules that apply about this, or is this a lawyer question?

Thank you!!

Dave