Bing found the following results
Smog - National Geographic Society
Smog | Description, Causes, Effects, & Types | Britannica
Smog - Wikipedia
AirNow.gov
Learn About the Causes and Effects of Smog - Treehugger
What Causes Smog? - Caltech Science Exchange
Smog, Soot, and Other Air Pollution from Transportation
Air Pollution | CDC - Centers for Disease Control and Prevention
Air pollution - World Health Organization (WHO)
What is smog and how can it be prevented?