Will oxygen ever be replenished in an underground bomb shelter with almost no ventilation?
Subtle air currents will ensure that oxygen and carbon dioxide will mix, especially due to air currents from temperature variations (convection currents) Their mass is not dramatically different from one another so they mix quite well. Of a greater concern is the presence of other, heavier gases from outside. Gases from vapourised fuel (petrol and diesel) stay close to the ground in still conditions and it’s possible if there was a fuel container nearby, the shelter could fill with heavy vapours. There have been MANY cases where people go to work inside below ground level tanks and are overcome by fumes in seconds. Even those who go down to rescue them will faint too and there’s been cases where 2 or 3 guys are found dead at the bottom of quite shallow tanks. Sewer workers go on very specialised courses to learn to use breathing equipment before they are licensed to go below ground. It may be that yes, oxygen was not being replenished very well in your shelter, so breathing was difficu
