Coal furnaces being used to heat houses. Used to be a very common smell around here every fall/winter. My grandpa burned coal until sometime in the early 90s when dad was no longer able to get the grade of coal he wanted.
we moved into the "haunted house" when I was in third grade...had to learn how to check/shake down/feed the coal furnace when I got home from school (Mom and Dad got home later than school let out).