Please don't take this the wrong way, but it's only we health anxious types that would smell smoke and even consider phantom smells. Non-anxious people would just presume it was something outside.

I live in Sheffield and there was one day this summer where the whole city smelt of smoke, and it was moorland fires all the way in Staffordshire. It's been a very warm, dry summer and autumn and there are a lot of fires around in the countryside, with the smoke smell drifting for several miles, way out of sight of where it's come from.

Now stop Googling