News

Study of winter ozone pollution moves forward

By Kevin Ashby
Vernal Express
April 2011
Niel Holt

EUSEP2 investigators Randy Martin, Kori Moore, Matt Bush, and Crystal Viator prepare to launch a meteorological tethersonde at the Red Wash site.

Ozone pollution has been a recognized problem in urban areas for more than 50 years.

The standard wisdom all these years has been that ozone pollution is only a big city problem, and that it only occurs in the summer. Air quality researchers were surprised, therefore, when they first began detecting significant ozone concentrations in a few rural areas during the winter months — first several years ago in the Upper Green River Basin near Pinedale, Wyo., and then during the winter of 2009-10 in the Uintah Basin.

It should be emphasized that ozone can play a beneficial role, depending on where it is located. The ozone layer that resides high in the stratosphere blocks a major portion of the sun's ultraviolet radiation. Without this beneficial and natural filtering, life on Earth would probably not exist.

However, when found closer to the planet's surface, that same ozone, in high concentration, poses a health hazard to humans, wildlife and plants.

Though not part of any federal regulatory effort, ozone measurements obtained by the Environmental Protection Agency during the winter of 2009- 10 in the Uintah Basin have motivated a proactive strategy on the part of local officials.

Scott Hill, Marc Mansfield, and Dan Schoales prepare to measure vertical meteorological data to 1,200 feet.

At a test site in Jensen, EUSEP2's Scott Hill, Marc Mansfield, and Dan Schoales prepare to measure vertical meteorological data to 1,200 feet.

These officials are aware of federal regulations stipulating that during actual, certified regulatory monitoring, unacceptably high ozone measurements taken over three consecutive years would require that any associated county be designated as a "nonattainment" area. They also were aware that any county so designated would then be required to design a technical plan for reducing its ozone concentrations.

While no such federal regulatory ozone monitoring had begun in the Uintah Basin, county commissioners were unwilling to play a passive role.

The counties' concerns regarding the winter 2009-10 ozone readings were compounded further by the absence of information to explain the extent and cause of the high ozone levels. Commissioners determined that any solid management strategy on their part would need to be preceded by and based on solid scientific evidence and expertise.

It was at this point that the Uintah County Commission approached the Eastern Utah Secure Energy Program & Partnership (EUSEP2) to perform a detailed study of winter ozone in the Basin during winter 2010-11.

EUSEP2 was established to provide technical leadership and capabilities for proactive, environmentally responsible energy development and eastern Utah. Based at Utah State University's Bingham Entrepreneurship and Energy Research Center in Vernal, the program's major partners include Utah State University's Energy Dynamics Laboratory; the Idaho National Laboratory; a federal lab in Idaho Falls, Idaho, with considerable energy expertise; the Logan and Vernal campuses of Utah State University; and the Utah Science, Technology, and Research Initiative (USTAR).

The partnership continues to expand through relationships with other universities, laboratories, and industries in the western United States and Canada.

Although the exact cause of the high ozone in the region is not yet completely understood, many general facts are known. Most of the ozone in the atmosphere is formed indirectly in a complex sequence of chemical reactions that are stimulated by sunlight, and that involve other pollutants, known collectively as "ozone precursors."

Because the reaction is driven by sunlight, ozone is normally a summertime problem. The intense summer sun, sitting high in the sky, can generate significant ozone production. The winter sun in the Uinta Basin would normally be too weak to fuel such production were it not for the relatively high altitude and ubiquitous snow cover.

The higher altitude allows less attenuation of incoming sunlight by the atmosphere, while snow on the ground permits the sun's rays to be reflected rather than absorbed. The decreased filtering and enhanced reflection more than compensate for the natural seasonal reduction of light intensity.

Thermal inversions also play a significant role.

Cold air sinks into the Basin and becomes stagnant, allowing the buildup of ozone precursors, and, ultimately, of ozone itself. In other words, the necessary ingredients for ozone in the Basin are sunlight, snow cover, thermal inversions, the presence of sufficient ozone precursors, and perhaps other factors yet to be discovered.

It is also known that other natural and man-made chemical reactions help reduce ozone levels, often decreasing the concentrations after dark. So even during a strong thermal inversion, the ozone concentration rises and falls with the sun.

This "ozone scavenging" is beneficial since it means that long-term exposure is somewhat minimized. But when the depletion can't keep up with production and carry over buildup, ozone concentrations can increase dramatically.

EUSEP2 researchers are working to determine the ozone precursors most active in the Basin in an effort to provide data vital to the region's attainment status. Were an appropriate, cost-effective remediation plan required in the future, EUSEP2's investigation of the precursors and the atmospheric processes responsible for the ozone formation would prove absolutely essential.

Researchers have been active throughout the winter monitoring levels of both ozone and ozone precursors at many sites in Uintah and Duchesne counties. The state Division of Air Quality, the U.S. Bureau of Land Management, and the National Park Service have also contributed data, personnel, and equipment to the effort.

In addition, numerous Duchesne and Uintah County citizens, firefighters, and city officials have also contributed greatly to the ongoing effort.

A full report of the 2010-11 study is being prepared and findings will be made available later this spring, once the data have been fully compiled and verified. The study will continue at least through the winter of 2011-12.