here in my location smelling smoke where there is no reason for it is called a hallucination. it is part of many mental disorders and normal for some people too. for me it was part of my CPTSD as in I was abused in a mine shaft and during the abuse there were fires around outside and in homes in the area (wood stoves, fireplaces) so now even though I no longer relive the trauma's (flashbacks) I sometimes smell smoke. I also love to go camping so sometimes when I just want to get away I will have the smoke hallucination that has been tracked back to camp fires.

in 2013 America went to a new standard of mental disorders. as part of this CPTSD got thrown out, discontinued. everything it was became part of other mental disorders. which means my CPTSD problems are no longer called CPTSD they are now called psychosis (having hallucinations) and other mental disorders.

my suggestion contact your or a treatment provider, they can help you to discover whether this is normal or a mental\physical health problem with in you.