'smog' originates from English, specifically a blend of 'smoke' and 'fog', where 'smoke' meant 'the visible vapor and gases given off by a burning or smoldering substance' and 'fog' meant 'a thick cloud of tiny water droplets suspended in the atmosphere'.

'smog' was coined in the early 20th century as a portmanteau of 'smoke' and 'fog', reflecting the combination of these two elements in polluted air.

Initially, it meant 'a combination of smoke and fog', but over time it evolved into its current meaning of 'air pollution caused by a mixture of smoke and fog'.