If it were me, and my 3 cats, I would not move into that apartment without a full disclosure of what fumigation chemicals are being used.
The most recent toxic gas combination used for 'tenting' is from DOW Chemicals 'Vicane' which is sulfuryl flouride with the additive chloropicrin.
These...
I've tried 20 Mule Team Borax (Boraxo) as described years ago, after having a flea infestation on the carpets. It worked very well, and I haven't seen any fleas since. I know someone who used Diatomaceous Earth , it worked but it did clog the vacuum cleaner. I have also used Nitenpyram...