Rad said:
This will be an "emergency" fumigation (not preventative), because the roaches are already in the building. Will they use the same chemicals?
They might use the same ones, if you are concerned you can just tell them to spray outside the windows and drainers, or just use the gel. You must know that
you are not obliged to let them in if you do not want to. Even if you are renting, they cannot force you to let them spray anything you do not trust, and you also have the right to know what it is exactly that they are using.
It is very possible that since a lot of people go on vacation trips on Dec, Jan and Feb, many apartments have not been fumigated, hence the more roaches you have noticed.
Again, I never had any issues and I have moved 13 times all over the city so I have lived in many different buildings.