A small apartment with no balcony and a male cat that when he shits, the smell transcends you in a different dimension. Luckily, I had a vent hole in the wall and mounted an extractor fan on the litter box (with a Noctua PC fan for quietness and low power drain) that constantly extracts the smell out of the box (and apartment) I sit at the last floor so I am not intoxicating anyone above.