.California, USA
The federal air-quality data site AirNow reported a US Air Quality Index peak of 422 for South Lake Tahoe. (Photo credit: PTI)

  • The culprit is the 126,182-acre Caldor Fire
  • The last time the area experienced anything near this week's smoke, she said, was during the Rim Fire
  • The Caldor Fire is the state's third-largest blaze