I lost the ability to smell a particular smell due to an exposure to solvents years ago. It has never fully come back. I had always assumed that simply meant I had permanently destroyed my ORNs for that smell. However, I have recently read that ORNs are replaced every 60 days.
Is it possible to lose all ORNs for a smell and have them never come back? I'd love to know whether my long term loss of smell is due to something cognative, or whether it is a complete lack of inputs from the nose.