The list below shows the areas with the highest NowCast AQI for the current hour. The AirNow system automatically generates this list every hour, based on the areas with the highest NowCast AQI for ozone or particle pollution. Because air quality can change during the day, the areas on this list may change throughout the day, too. Note: This list is not used for regulatory purposes, and it does not indicate an area’s status in meeting National Ambient Air Quality Standards.