from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Air pollution produced by the action of sunlight on hydrocarbons, nitrogen oxides, and other pollutants.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. air pollution caused by photochemical reactions involving hydrocarbons, nitrogen oxides and other pollutants, especially in still air over cities
Sorry, no etymologies found.