I live on the 1st floor of a block of 4 flats. On my floor there's us and our neighbour...below are two more flats.
The air in the stairs and communal area gets stuffy with cooking smells from 4 homes....I advocate opening the door to the gardens daily...twice daily at least.
My neighbours all prefer the door shut all day and to have numerous stinky air fresheners outside their doors. 
Today I cam in to find my neighbour on my floor has lit an oil burner...the kind with a little candle under it and left it outside her door.
It is to one side but I am concerned it's not safe...also I have two children who could kick hot oil over their ankles. AIBU to ask her to get rid of it?
To be fair my DC don't really go near her door but it's literally only 4 feet from mine...also whatever she's burning stinks of Dettol! The bowl is full to the brim with oil too.