DMR states plainly that we generally cannot smell ammonia below 10 ppm. Read that carefully. Your nose can tell you ammonia is present. It can never tell you the level is low enough. Those are different statements, and crops are lost on the difference.
A nose also tires. After a few minutes in the corridor you stop noticing a smell that has not changed. That is olfactory fatigue, and it makes the second sniff less reliable than the first. Never deliberately breathe compost air to test a batch. Ammonia is an irritant gas and a tunnel is a confined space.