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Ozone air pollution threatens remote mountain landscapes

Date: October 05, 2015


Portable ozone monitor at Trout Creek Pass, Colorado.
Portable ozone monitor at Trout Creek Pass, Colorado.
Ozone (O3) is the most widespread air pollutant and is highly toxic to vegetation. It can kill leaf tissue, reduce plant growth, and make plants more susceptible to other stresses such as drought. Ozone is an added threat in high elevation ecosystems where plants already struggle to survive. It can also impact humans by impairing lung function, especially for children, the elderly, and those with breathing problems.

Studies show that oil and gas development in the Rocky Mountains can increase O3 concentrations. Drilling and pumping rigs that burn fossil fuels produce chemicals that can interact in the air to produce O3. Oil and gas wells in the western U.S. are often in or near national forests and sometimes near Class I Wilderness areas where federal land managers are required by the Clean Air Act to protect air quality related values such as plants, animals, and soils from air pollutants. Yet little is known about ambient O3 concentrations at many of these remote locations.

The U.S. Environmental Protection Agency has proposed strengthening the National Ambient Air Quality Standard (NAAQS) for O3. The EPA has concluded that the primary NAAQS, which is based on an hourly average concentration and used to protect human health, is inadequate to protect sensitive ecosystems, and the agency has proposed a new secondary standard targeted to protect non-urban and non-crop natural vegetation and ecosystems. The EPA has specifically indicated that a strengthened primary standard for ozone will not adequately protect sensitive tree species in high-elevation western ecosystems where little O3 data are available.

Key Findings

Station researchers are using a portable battery powered monitor to evaluate O3 at several high-elevation, remote locations in the Rocky Mountain West. Findings show:

  • Significant year-to-year differences in O3 at each site.
  • Average 8-hr O3 concentrations exceeded the current primary NAAQS of 75 parts per billion (ppb) at several sites and the proposed new standard of 70 ppb at additional sites.
  • The proposed new secondary NAAQS of a three-month 12-hr ozone index (i.e., W126) of 13 ppb-hrs was exceeded at most sites and mid-level O3 concentrations were an important contributor to the secondary standard exceedances.
  • O3 was persistent at night, particularly at higher elevations, indicating nighttime exposure of vegetation to O3.
  • O3 was sometimes highest in late spring, and at high altitude sites (>3000 meters), suggesting a stratospheric source of O3.

Research findings will allow national forests to determine O3 levels in remote areas where air quality related values are unknown, determine if O3 at these sites exceed the federal standard, and examine long-term changes in O3 in remote regions.

Featured Publications

Musselman, Robert (Bob) C. ; Korfmacher, John L. , 2014
Korfmacher, John L. ; Musselman, Robert (Bob) C. , 2014
Heath, Robert L. ; Lefohn, Allen S. ; Musselman, Robert (Bob) C. , 2009
Paoletti, Elena ; Bytnerowicz, Andrzej ; Andersen, Chris ; Augustaitis, Algirdas ; Ferretti, Marco ; Grulke, Nancy ; Gunthardt-goerg, Madeleine S. ; Innes, John ; Johnson, Dale ; Karnosky, Dave ; Luangjame, Jessada ; Matyssek, Rainer ; McNulty, Steven ; Muller-Starck, Gerhard ; Musselman, Robert (Bob) C. ; Percy, Kevin , 2007
Musselman, Robert (Bob) C. ; Lefohn, Allen S. ; Massman , William J. , Jr ; Heath, Robert L. , 2006
Musselman, Robert (Bob) C. ; Zeller, Karl F. ; Nikolov, Nedialko T. , 1998

Principal Investigators: 
Forest Service Partners: 
Rocky Mountain Region
Arapahoe/Roosevelt National Forests
Pawnee National Grassland
White River National Forest
Pike/San Isabel National Forests
Grand Mesa/Uncompahgre/Gunnison National Forests
San Juan National Forest
Nebraska National Forest
Medicine Bow/Routt National Forests
Black Hills National Forest
Intermountain Region
Ashley National Forest
External Partners: 
Colorado Department of Public Health and Environment - Air Resources Division
U.S. Environmental Protection Agency
National Park Service
The Wilderness Workshop
Air Resources Specialists
Friends of Mount Evans and Lost Creek Wilderness
Aspen Ski Co.
Eldora Mountain Resort
Snowbird Ski & Summer Resort
2B Technologies, Inc.