AirNow Action Days names are listed on AirNow.gov.
Action day names for AirNow reporting areas are defined upon creation of the reporting area in the system. After creation, they can be set from the Forecast tab on the AirNow-Tech website as specified in this forum post
If the action day name or URL is incorrect or missing from the AirNow Action Days page please send an email request to AirNow Data Management Support at info@airnowtech.org