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

Typically, sales of the gas are restricted during the summer due to the volatility of ethanol and its contribution to smog, but the Farm Bureau maintains that new studies show the blend is non-polluting.

From Los Angeles Times • Mar. 29, 2026

The Altadena schoolgirl was witnessing the Big Bang of L.A. smog.

From Los Angeles Times • Mar. 26, 2026

“Today we can say all aboard on what will be the highest ridership light rail in the country, easier commutes, less smog, more access to housing.”

From Los Angeles Times • Mar. 26, 2026

As wretched as smog was, Angelenos were not about to stop driving their cars, so the cars had to change.

From Los Angeles Times • Mar. 26, 2026

We use the fence to help us climb up onto the garage and then we look up at the three or so stars we can see through the light pollution and smog.

From "Boy21" by Matthew Quick

Related Words

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