: a fog made heavier and darker by smoke and chemical fumes
also
: a photochemical haze caused by the action of solar ultraviolet radiation on atmosphere polluted with hydrocarbons and oxides of nitrogen especially from automobile exhaust
Examples of smog in a Sentence
the city's smog was once so bad that darkness often prevailed, even at noon
Recent Examples on the Web
Sulfur dioxide and resulting vog (volcanic smog) can irritate eyes and respiratory systems, particularly in people with asthma and other chronic lung conditions, according to the Hawaii State Department of Health.
—
Daniel Orton, MSNBC Newsweek, 3 Sep. 2025
Key Background The link between fossil fuels and air pollution was first proven in the 1950s, spurred by smog blankets covering Los Angeles and New York City.
—Mary Whitfill Roeloffs, Forbes.com, 22 Aug. 2025
The fact that the mural and the garden coexist next to the concrete and smog of California’s target freeway adds another layer.
—Carlos Rico, San Diego Union-Tribune, 19 Aug. 2025
According to the district, the pollutants contribute to smog and other particle pollution, the kind of which can create Spare the Air conditions.
—Rick Hurd, Mercury News, 15 Aug. 2025
See All Example Sentences for smog
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Daniel Orton, MSNBC Newsweek, 3 Sep. 2025
Key Background The link between fossil fuels and air pollution was first proven in the 1950s, spurred by smog blankets covering Los Angeles and New York City.
—Mary Whitfill Roeloffs, Forbes.com, 22 Aug. 2025
The fact that the mural and the garden coexist next to the concrete and smog of California’s target freeway adds another layer.
—Carlos Rico, San Diego Union-Tribune, 19 Aug. 2025
According to the district, the pollutants contribute to smog and other particle pollution, the kind of which can create Spare the Air conditions.
—Rick Hurd, Mercury News, 15 Aug. 2025
See All Example Sentences for smog
Cite this Entry
“Smog.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/smog. Accessed 5 Sep. 2025.
Copy CitationKids Definition
smog
noun
ˈsmäg 
also ˈsmȯg
: a thick haze caused by the action of sunlight on air polluted especially by smoke and automobile exhaust fumes
Etymology
from smoke and fog
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