Smoke from a house fire is by definition a contaminate.

Back in the dark ages ('80's) I would approach older home owners & offer them a buyout with them holding the note at an attractive interest rate.

During our inspection a few months back we could smell smoke in the unit.

There were other concerning items like a hardwired smoke alarm taken down, the new fridge handle that I had purchased ($60) was not on the fridge, and there was fallen paint and a large water stain on the kitchen ceiling (2 baths and wash/dryer above that area).

The Village where the building is has now sought a demolition order for the building due to; smoke alarms, improper boiler venting, leaking gas lines to stoves, and leaking roofs over the front and rear entrances.

What's the custom for allowing, not allowing, charging an extra deposit for, or any special considerations, (or none) for the issue of smoking in your apartments?

And if you're having trouble leasing the unit, I would probably drop the restriction on being a non-smoker and just say they can't smoke in the unit (although they likely will). 

I have found good tenants in that price range to be a challenge, specially finding folks who dont smoke!

Sometimes the stores close, but they still have time left on the lease and are just going dark. 

Getting any Joe blow will get you smoked.