@yourfutureex
I would have to read the actual patent to answer those questions. @thomas posted this link to it in another comment.
https://worldwide.espacenet.com/patent/search/family/022895576/publication/US4320756A?q=US4320756
@dgar I think I might rather breathe the smoke than the sewer air.
The bathtub in our en-suite went unused for a few months, and the water in the air-lock s-bend evaporated. It took a day or two to work out what the problem was and why the room smelt like shit & death. Poured some water down the bath drain and the smell went away instantly!
Honestly - wrap a wet towel around your head & breathe through that, or just jump from the 15th floor window and hope there's a pool beneath you.