# smog

/ˈsmɑɡ/ (US) · /smˈɒɡ/ (UK) · CEFR B1 · Noun

Source: https://englishreference.com/word/smog
Updated: 2026-05-09

## Definition

a thick, dirty type of air pollution that looks like a mix of smoke and fog. It usually happens in big cities where there are many cars and factories.

For teachers: a form of atmospheric pollution consisting of a mixture of smoke and fog, or chemical fumes. Often results from the interaction of sunlight with industrial emissions and vehicle exhaust.

## Examples

- The city is covered in thick smog today.
- Local authorities issued a health warning because the smog was so thick that it reduced visibility on the highway.
- Heavy industrialization combined with a lack of wind created a persistent layer of smog that hung over the valley for several weeks, prompting calls for stricter emission controls.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.