[![enter image description here][1]][1]


  [1]: https://i.sstatic.net/ALHejv8J.jpg

From this picture from Ep 2 Season 1, ***Madmen***, I have circles two cigarratte in red and three smoke alarms in black in the ceiling.

I am assuming they are smoke alarms. If they are, why are they not triggered by smoke coming from cigarratte in the office?