How do we know a previous drug house is safe?

[Warren Marshall]

Hey guys, 

We just went conditional on our second Airbnb property, this one is a was considered a "Flop House" by the sellers agent.   Which supposedly is a drug house that the door is always open so people can sleep there when ever they want...    We will be changing out the floors, and paint but we need to know how to be confident there isn't danger to the renters or construction crew.    Does anyone have helpful tips?   Main concern is Fentanyl as I understand that it is very high risk and hard to get rid of. 

Thanks in advance, 
Warren