smog

noun

1. (countable, uncountable)A noxious mixture of particulates and gases that is the result of urban air pollution.

   “A widow since 1967, she lives now in Honolulu because, she says, she can enjoy the Californialike climate without the smog.”

   “Everyone smoked so if the auditorium was full, the whole room would be filled with smoke in next to no time. It was like the legendary London smog of the 1950s in there sometimes. You took it in turn to “flash the ash” as it was called.”

verb

1. (informal)To get a smog check; to check a vehicle or have it checked for emissions.

   “If the car is more than five years old, you'll have to have it smogged before you can register it.”