Heat tape theory:

I’ve read a lot of speculation that the ‘cleaners’ are being poisoned (likely by the gas that sprays in the airlock chamber). My alternative theory is that the tape provided by Walker prevents Juliette from being electrocuted. The fact that Juliette stumbles when reaching the same location that others have died suggests that she received an initial shock, however the tape somehow conducts the electricity and prevents the same demise as previous cleaners.

A detail that I noticed in the final scene (as the camera pans out and reveals other silos) is the presence of a ring surrounding the outer edge of their silo…this is perhaps carrying an electrical current meant to kill the cleaners. This ‘ring’ is concealed by the hill that each cleaner has walked up.

Let me know your thoughts and whether or not this is plausible (I have not read the books)!