Wyoming’s winter ozone in check, so far

It’s ozone season in Wyoming’s Upper Green River Basin, but so far the region has avoided any prolonged spikes of high ozone concentrations, according to officials at the Wyoming Department of Environmental Quality.

“We have not exceeded the 8 hour ozone standard so far this year (January 1 through Feb. 8 data). In fact, we have not recorded an 8 hour value greater than 60 ppb yet this year,” Cara Keslar, DEQ’s Ambient and Emissions Monitoring Program Manager, told WyoFile via email.

Seperation facilities in the Pinedale Anticline

Separation facilities in the Pinedale Anticline have been consolidated to reduce emissions. (Dustin Bleizeffer/WyoFile - click to enlarge)


At ground-level, ozone can cause nose, throat and eye irritation, and shortness of breath. It can be extremely dangerous — even deadly — to the elderly, children and those with respiratory problems. Last winter, ground-level ozone concentrations in the basin area spiked above the federal 8 hour standard of 75 parts per billion on 13 occasions. The highest 8 hour average ozone concentration was measured on March 2, 2011, at 124 ppb — higher than Los Angeles’ worst ozone day.

The ozone spikes are the result of pollution emissions from natural gas drilling and production activity in the Pinedale Anticline and Jonah fields. When there’s an inversion, volatile organic compounds (VOC) from natural gas facilities and nitrogen oxides (NOx) from tailpipe emissions are suspended low in the valley — along with smoke from wood-burning stoves and other background pollution. If the valley is blanketed in snow, then the VOCs and NOx are exposed to direct sunlight and light reflected from snow, causing a photochemical reaction that creates ozone.

DEQ currently provides daily forecasts to determine the probability of high ozone days. Click here to sign up for daily email updates.

So far this year there have been six days that the hourly ozone was measured at greater than 60 ppb, according to Keslar. Two of those days the hourly ozone was greater than 70 ppb.

“The highest values are occurring at the Boulder monitor, however, the Juel Springs, Daniel, and Big Piney monitors have also recorded slightly elevated ozone this year,” Keslar said. “It should be noted that these values have not gone through the data validation process yet, however, all stations have undergone independent quality assurance audits for this quarter and have passed.”

Keslar said there have been some issues with communications and power outages at some of the Sublette County monitoring stations this winter, and DEQ staff is working to rectify the problems.

Last year, the U.S. Environmental Protection Agency was expected to lower the 8 hour ozone standard to 60 or 70 ppb, but the Obama administration backed off of the ruling. Sublette County is currently in “non-attainment” status for ozone, which means state regulatory officials must draft a plan that will bring the region back into compliance with federal air quality laws.

— Contact WyoFile editor-in-chief Dustin Bleizeffer at (307) 577-6069 or dustin@wyofile.com.

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Published on February 10, 2012

  • maria katherman

    I’m glad to hear things have eased up a bit on the Pinedale anticline, but I live between Glenrock & Douglas in the new frontier of oil & gas drilling and we are having our first winter of sever air pollution. This may be news to DEQ, but on those cold, still, inversion mornings–so beautiful along the river in the past–there is now a brownish haze & vague burning feeling in the bronchioles. We are hemmed by the bookend power plants in Glenrock and Wheatland, but what is new are the 16+ (number going up to fast to count ‘em!) flares, the truck traffic and the dust. And no monitors, of course.

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