the problem we had with our air handlers was bifenthrin. probably came with PBO. too, but it wasn’t on ODA’s radar at the time, so we wouldn’t have failed for it. was almost 2 years between last documented use & first 3rd party test.
PBO seems to be used not as a pesitcide, but as an “enhancer” in some pyrethrin/permethrin formulations. not sure how long it sticks around, but boy howdy I can tell you that bifenthrin lasts forever!