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. 


The AQD met with the public in Pinedale on May 31, 2016 to gather information for consideration by the AQD regarding a Phase II approach to address emissions from existing sources and address new growth in the UGRB Ozone Nonattainment Area.  In addition to the input received during the meeting, the AQD will accept written input in regard to the information gathering questions until the close of business on July 8, 2016.  

Written input should be submitted to DEQ/AQD Ozone Team, 200 W. 17th St., Cheyenne, Wyoming, 82002, or faxed to 307-635-1784, by the close of business on July 8, 2016. 

Winter Ozone Updates

AQD will provide the community with Winter Ozone Updates that discuss the current day and following two days weather forecast and how that is anticipated to impact ozone levels.  Winter Ozone Updates are geared specifically towards making sure you have the information you need to decide whether to limit outdoor activity.  Current information on ozone levels at the AQD’s monitoring stations can be found at

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.

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.