CASPER, Wyo. (AP) — Wyoming air quality regulators are working on preparations and forecasts for the 2021 winter ozone season in the state’s Upper Green River Basin.
A combination of weather conditions and human activity can generate high levels of ozone, an air pollutant that blossoms when sun reacts with emissions or other pollutants. Add in meteorological conditions like cold temperatures, a lack of wind or snow cover, and ground-level ozone thrives.
Between January and March, Sublette County and portions of Lincoln and Sweetwater counties often record higher levels of ozone, the Casper Star Tribune reported.
The Wyoming Department of Environmental Quality’s Air Quality Division issued three ozone outlooks and five ozone action days in 2020. On ozone action days, regulators ask industry and residents to minimize emissions containing volatile organic compounds and nitrogen oxides.
Last year, regulators also recorded two days — Jan. 21 and Feb. 22 — where ozone levels exceeded the federal limit — an eight-hour rolling average of 70 parts per billion (ppb). Once March rolled around, snow depth and ozone levels dramatically dropped.
This winter will mark the 15th year Wyoming regulators have monitored the region for ozone and analyzed the data.
Concerns over dangerous levels of ozone are not new to residents around Wyoming’s Upper Green River Basin.
In 2012, the Upper Green River Basin was deemed a “nonattainment zone,” meaning the air conditions did not meet the National Ambient Air Quality Standards.
Sublette County and portions of Lincoln and Sweetwater counties are now considered a marginal non-attainment zone. The areas received a determination of attainment in July 2015, but the area has yet to be officially re-designated by the EPA.
However, the air quality team said on Dec. 17 it would be taking steps with the EPA to re-designate the area as in attainment this year.
Wyoming air quality regulators have also undertaken mitigation efforts in the basin, imposing more stringent inspections and emission capture requirements for industry.
In 2020, Wyoming inspectors conducted 939 site visits and 29 inspections to facilities at risk of contributing to heightened ozone levels in the region.