Should we as a species stop nice smelling things entirely.
Intuitively I'd guess the scented candle is worse than the flowers. I doubt soot and vaporized wax are good for you.
We already had the same conversation about the automatic perfume spray machines; we had them over the dinner table, on hallways etc. Not so great when you are a tall person, and all of a sudden you get sprayed in your face because you happen to be standing in-front of the machine.
If someone's not cleaning that, I also have some bad news for them about their washing machine.
I need microparticles in my nose so that it can detect things. Some of the things it detects are pleasant. If one of those pleasant things should stop producing microparticles for health reasons, make that argument instead?