The mechanics of a smell or odor

Factual Questions
1

I have never ran acrosss any odor that would not eventually disapate. If something is giving off a smell is it safe to assume it can only give off so much before it is simply gone? As in a dead body odor left in a car or apt.

I have found baking halibut leaves a lingering smell for sometimes 3 days, smoke smells from small kitchen fires can be stubborn also but they all seem to go away.

 Is it possible for a smell to linger for say a year or longer even after the source has been cleaned up?
2

to smell a chemical molecule(s) have to make it into your nose.

so the stink has to move. if you clean up the bulk substance and have some ventilation then the smell will be gone.

now some substances don’t take much to stink. if it might have some oily character then it might stick to plastics or paints for a long time. so some pepper smell might stay in plastic food containers for a very long time because some pepper is really still there.