smog

noun \ ˈsmäg , ˈsmȯg \

Updated on: 19 May 2018

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

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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

Even after everything has settled down, the threat of volcanic smog and acid rain may linger.

— aj willingham, CNN, "Volcanoes. Geysers. Earthquakes. Mother Earth sure seems angry right now," 14 May 2018
More than 1,000 residents in the area were told to evacuate and warned about the health hazards of volcanic smog caused by sulfur dioxide released through fissures.

— jennifer earl, Fox News, "Is Hawaii's Kilauea volcano going to explode? What Mount St. Helens and other eruptions have taught us," 10 May 2018
For months, environmental groups have said the new regulations advanced under former President Barack Obama would save money by reducing health care costs such asthma attacks and heart attacks on days of elevated smog.

— lee bergquist, Milwaukee Journal Sentinel, "EPA dramatically narrows areas of Wisconsin that will face tougher regulations for smog," 1 May 2018
Ground-level ozone, also referred to as smog, is created when nitrogen oxides and volatile organic compounds form a chemical reaction from sunlight.

— frank kummer, Philly.com, "Philly fails to meet smog standards, EPA says," 1 May 2018
The pollutant is a key contributor to lung disease and smog, which contributes to climate change, the settlement notes.

— mary ellen klas, miamiherald, "VW has to pay Florida $166M after emissions scandal. How should we spend the money? | Miami Herald," 27 Apr. 2018
Children, people with respiratory problems such as asthma, and adults who exercise outdoors are most vulnerable to smog.

— frank kummer, Philly.com, "Philly fails to meet smog standards, EPA says," 1 May 2018
More: California has eight of 10 most polluted U.S. cities The two pollutants studied were carbon monoxide and nitrogen oxide, both of which contribute to ground-level ozone (smog).

— doyle rice, USA TODAY, "The USA's long battle against air pollution isn't over yet, as air quality improvements are slowing down," 30 Apr. 2018
Scientists say rising temperatures from climate change will make smog tougher to control by boosting the photochemical reactions that generate ozone pollution.

— tony barboza, latimes.com, "Slowdown in emissions reductions could explain stalled progress on smog, study finds," 30 Apr. 2018

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

in the meaning defined above

See Words from the same year

smog Synonyms

Synonyms

fog, haze, mist, murk, reek, soup;

Other Climate/Meteorology Terms

monsoon, occlusion, ozone, rime, squall, zephyr

SMOG Defined for English Language Learners

smog

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

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.