Emissions concern
(Other definitions for smog that I've seen before include "Pollutant fog" , "Polluted atmosphere" , "Smokey fog" , "Thick polluted mist" , "Man-made atmospheric pollution" .)
(Other definitions for soot that I've seen before include "Carbon dust from fire" , "Something stuck down the chimney" , "Smut" , "Carbon deposit from burning" , "Carbon black" .)