Meaning of photochemical smog

pho'tochem'ical smog'

Pronunciation: [key]
— Meteorol. Meteorol.
  1. air pollution containing ozone and other reactive chemical compounds formed by the action of sunlight on nitrogen oxides and hydrocarbons, esp. those in automobile exhaust. Also called
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.