smog

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noun \ˈsmäg, ˈsmȯg\

Definition of smog

: 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

smogless

play \ˈsmä-gləs, ˈsmȯ-\ adjective

See smog defined for English-language learners

See smog defined for kids

Examples of smog in a Sentence

the city's smog was once so bad that darkness often prevailed, even at noon

Recent Examples of smog from the Web

The area including southern Indiana experienced unhealthy smog on 19 days in 2016.

— james bruggers, The Courier-Journal, "Smoggy skies return to Louisville area as officials call a pollution warning," 18 July 2017
That year, smog was responsible for a third of all deaths in the country.

— david wallace-wells, Daily Intelligencer, "When Will the Planet Be Too Hot For Humans? Much, Much Sooner Than You Imagine.," 9 July 2017
Cars, trucks and other vehicles also emit black carbon and ozone-producing gases—pollutants that create smog, drive poor air quality and contribute to acid rain.

— erin blakemore, Smithsonian, "France May Say ‘Au Revoir’ to Fossil-Fueled Vehicles," 7 July 2017
EDF said that reducing leaks would keep large quantities of smog-forming volatile organic compounds, cancer-causing benzene, and methane from being emitted into the air.

— robert rhoden, NOLA.com, "Florida man sits on gun, accidentally shoots himself in groin: report," 3 July 2017
The Environmental Protection Agency says Atlanta does meet smog standards.

— manuel bojorquez, CBS News, "Air pollution levels considered safe can still shorten lifespans, study shows," 28 June 2017
The fuel’s popularity waned over the past several years as renewable power and natural gas made gains and China moved to curb dangerous levels of urban smog from burning coal.

— katy daigle, The Seattle Times, "Coal on the rise in China, U.S., India after major 2016 drop," 26 June 2017
Nitrogen oxide is linked to smog formation and respiratory problems.

— david shepardson, Fortune, "EPA Suspected Fiat Chrysler Was Using ‘Defeat Device’ in 2015," 17 June 2017
The Targeted Air Shed Grant Program, which grants funds to local, state and tribal governments to reduce smog-causing air pollution.

— dino grandoni, Washington Post, "The Energy 202: EPA's budget finds unexpected defenders in Congress," 16 June 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'smog.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of smog

smoke + fog

NEW! Time Traveler

First Known Use: 1881

See Words from the same year

Other Climate/Meteorology Terms

monsoon, occlusion, ozone, rime, squall, zephyr

SMOG Defined for English Language Learners

smog

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noun

Definition of smog for English Language Learners

: fog mixed with smoke : a cloud of dirty air from cars, factories, etc., that is usually found in cities

SMOG Defined for Kids

smog

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noun \ˈsmäg\

Definition of smog for Students

: a fog made heavier and thicker by the action of sunlight on polluted air

History for smog

The word smog was coined in England in 1905 by combining the words smoke and fog. The person who coined the word wanted to more accurately describe the atmosphere in London caused by fog mixing with smoke from coal furnaces used for heating. In the United States smog often describes any sort of visible air pollution, such as the haze around cities produced by automobile exhaust affected by sunlight.

Medical Dictionary

smog

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noun \ˈsmäg also ˈsmȯg\

Medical Definition of smog

: 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