We have a tenant living below us who we know is smoking in her unit, because we can smell it in ours.Since we must give 24 hours notice before entering her unit, it is difficult to catch her in the act.Please help us with a foolproof way to prove that she is lying.Are there any chemical tests or air quality tests that we do not know about?

Well you would have to catch her actually smoking. But if you can smell the cigarette smoke in the unit that should be enough providing she is the only one there at the time.

While you must give her 24 hours notice before entering her apartment, you do not need any notice to knock on her door while holding a fire extinguisher and saying ''We smelled smoke upstairs in our apartment and thought something had caught fire down here...''

As already suggested, just knock when you smell the smoke wafting up. She will likely answer the door and you will see a cloud of smoke.

If she smokes, she is going to have ashtrays, lighters and ciggies stashed away somewhere. When you inspect, open up cabinets, drawers and closets - you cannot open her personal bureaus or drawers, just ''fixtures'' to your rental.

Check the garbage can, she has to dispose of the butts somewhere.