Hi Vlad; Yes, there is a fatal danger if they are not out of the apartment...!!! Lots of bug killers will gas or fog a unit that will KILL ANY living thing! You must get them OUT of there, and open all windows for at least 4 hours after "it's time" to return, BEFORE bringing the fuzzies back. That is NOT the way you want to learn what can kill them! Stay safe, be happy:) Gary & the gang of fur The pure of heart carry within a source of good. [Posted in FML issue 1586]