Bing found the following results
Smog - Wikipedia
Smog | Description, Causes, Effects, & Types | Britannica
Smog - National Geographic Society
AirNow.gov
Learn About the Causes and Effects of Smog - Treehugger
Smog, Soot, and Other Air Pollution from Transportation
Air Monitoring in Massachusetts | Mass.gov
What Causes Smog? - Caltech Science Exchange
What is smog and how can it be prevented?
Check a vehicle's inspection history - Bureau of Automotive Repair