HMS imagery fire and smoke imagery, below left, shows swaths of smoke over the Pacific northwest, the southeast, and the Rocky Mountains states. This may have helped cause the areas of Moderate AQI in the Southeast and in Northern California, seen the EPA AirNow AQI loop, below right, but the AQI around the other patches seems largely normal. Other notable features in the AQI loop are the large regions designated Moderate to Unhealthy for Sensitive Groups stretching from the Great Lakes region into the Mid-Atlantic and through much of the Pacific Southwest, as well as the stubborn patch over south Texas and other areas popping up in farther north in the Plains throughout the day.
EPA ozone measurements, below left, indicate that to be a probable cause for the elevated AQI in much of the Pacific Southwest. NRL NAAPS output, below right, shows sulfate over most of the U.S. east of the Mississippi, which could help explain the elevated AQI in these areas.