smog

American  

[smog, smawg] / smɒg, smɔg /

noun

1. smoke or other atmospheric pollutants combined with fog in an unhealthy or irritating mixture.

2. photochemical smog.

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verb (used with object)

1. to cover or envelop with or as if with smog.

smog British  

/ smɒɡ /

noun

1. a mixture of smoke, fog, and chemical fumes

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smog Scientific  

/ smŏg /

1. A form of air pollution produced by the reaction of sunlight with hydrocarbons, nitrogen compounds, and other gases primarily released in automobile exhaust. Smog is common in large urban areas, especially during hot, sunny weather, where it appears as a brownish haze that can irritate the eyes and lungs. Ozone, a toxic gas that is not normally produced at lower atmospheric levels, is one of the primary pollutants created in this kind of smog.

2. Also called photochemical smog

3. Fog that has become polluted with smoke and particulates, especially from burning coal.

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smog Cultural  

1. A haze or fog composed of water vapor, complex molecules, and suspended particles.

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Discover More

In North America, the primary cause of smog is pollution from automobile exhaust.

The Los Angeles basin, where pollutants can be trapped by inversions and the surrounding mountains, has frequent problems with smog, as do other major urban areas.

The word smog is a combination of smoke and fog.

Other Word Forms

• desmog verb (used with object)
• smoggy adjective
• smogless adjective

Etymology

Origin of smog

1900–05; sm(oke) + ( f)og ¹

Example Sentences

Our beautiful encircling topography of mountains and hills is a bowl ready-made by ancient plate tectonics to be filled with smoke and smog.

From Los Angeles Times • Mar. 26, 2026

All of L.A. believed, and official L.A. passionately hoped, that once the war was over and all those smokestacks shut down, the smog would vanish too.

From Los Angeles Times • Mar. 26, 2026

But the war ended, and the smog didn’t, and L.A. wiped its weepy red eyes and demanded some solutions, dammit.

From Los Angeles Times • Mar. 26, 2026

And now, to fuel the war effort, the big smokestacks on those big oil refineries were sending out big black plumes of gunk — and that had to be creating the smog, right?

From Los Angeles Times • Mar. 26, 2026

Dimple took a deep breath, acrid smog and wet mist and herby eucalyptus all mixing together in her lungs.

From "When Dimple Met Rishi" by Sandhya Menon

Related Words

• acid rain
• carbon dioxide
• fog
• smoke
• soot