Anyone know of any devices that can detect cigarette smoke?

Your nose?

shite

Apparently, airlines have had this technology in the lavatories for a couple decades. That or the flying cocktail waitresses have been lying to everyone.

Go to the apartment/s in question and ask to be invited in. While your there see if you can smell evidence they are smoking in the apartment. Unless they are extremely vigilant about airing the apartment out and liberal use of air fresheners it should be obvious. Make sure you inspect the bedrooms because if the are smoking in the living room they are probably smoking in bedroom.

Try talking to them also. While i'm sure they know they aren't supposed to do it, a simple reprimand and reminder of the consequences may be enough to get them to stop.

If you are worried about the legal consequences of taking action without "proof" don't worry about it. My uncle owns several apartment complexes and has had to fine and evict several people over the years for continuing to smoke in their apartments after being warned. One guy was dumb enough to sue him over it, saying that he had no proof. The neighbor's testimony, his his own testimony about the pungent smell and butts in the trash can when he inspected, and the three previous warnings he'd been given was more than enough to absolve him of any wrong doing.

Smoke detectors usually do a good job at detecting smoke.

Unit has active smoke detectors and nothing is picked up. Could be the 12 foot ceilings.

Start a monthly "air filter" replacement visit to protect your valuable central air units. Visit unannounced sometime the same week each month. Catch them slippin'.knock knock, key the door, announce yourself, then enter. Also trash placed outside in common areas is open season. They have no expectation of privacy once they place it there. If you catch them, assess them a smoke removal fee (deposit) and give them a warning.