From King Dictionary of Contemporary Englishsmogsmog /smɒɡ $ smɑːɡ, smɒːɡ/ ●○○ noun [countable, uncountable] SGPdirty air that looks like a mixture of smoke and fog, caused by smoke from cars and factories in citiessmoggy adjective
Examples from the Corpus
smogFlagged motorists will be notified by mail that they must get a smog check and have their autos repaired, Kniestedt said.Hydrocarbon smog from traffic; smoke from a coal-fired power station.So did women who gave birth after the thick London smog of 1952.The streets are clean, there's no smog to dull the sunshine, and the skyscrapers don't overpower.In sunlight, VOCs can react in the lower atmosphere with nitrogen oxides to generate photochemical smog.Ethyl Corp. says it reduces smog and presents no threat to cars or public health.On 75 days the smog was so bad that schoolchildren were advised to stay indoors.Eventually, smog-check stations are expected to electronically transmit smog certificates directly to the Department of Motor Vehicles.
Origin smog (1900-2000) smoke + fog