Why a Small Mandir Needs More Ventilation, Not Less
It seems backwards until you think about it. A large open mandir has a big volume of air above the flame and no walls to hold anything in, so smoke rises and disperses into the room. A small closed mandir has neither: the enclosed volume is a fraction of the size, and the doors keep everything inside it. The same lamp that leaves almost no mark on a large open shrine will darken the inside of a compact closed one within a couple of years. Small and closed is the worst combination, and it is exactly the combination most flats need.
Cutting both doors as lattice across their whole area is the answer to that. The front face becomes effectively open to air while still being a door you can shut, which is a different proposition from a solid door with a small vent or a lattice inset in one panel. It costs more, because jaali is slow work and a small door has proportionally more edge and more narrow bars than a large one. The marble sill at the threshold does the parallel job for heat and oil: it sits exactly where a diya is set down and where ghee runs, and takes what polished wood in that position would not. Everything is carved and polished by hand by master Indian artisans.