Winter Ozone

In 2005, the AQD recorded elevated ozone levels in the Upper Green River Basin. We know that the ozone exceedances are related to at least four factors: adequate amounts of precursor chemicals, snow cover, temperature inversions and low winds, and sunlight.

In the time since then, DEQ has been working to lower the ozone levels, conducting a series of studies on the area. This page is intended to provide the public and industry with information about past and current work, background information related to the ozone issue, current ozone data, technical documents and forms. 


During the 2017 winter ozone season, the AQD will no longer be issuing daily winter ozone updates for today, tomorrow, and the extended.  The AQD will still be forecasting during the winter ozone season, however, the public and industry will only be notified if an Ozone Action Day has been issued.  To receive Ozone Action Day notifications, sign up here.

Ozone Action Day Notifications

AQD will provide the community with Ozone Action Day notifications when they are issued.  AQD will issue an Ozone Action Day one day in advance when forecast weather conditions appear favorable for the formation of elevated ozone the following day.  Ozone Contingency Plans should be implemented upon one-day notice and everyone is encouraged to voluntarily reduce emissions. Please remember that current information on ozone levels at the AQD’s monitoring stations can be found at

Note: AQD winter ozone forecasting only takes place from January through March of each calendar year. 

For more information about Winter Ozone Updates, please call 1-888-WYO-WDEQ.


2017 Winter Ozone Season Update