Ozone Air Pollution Threatens Remote National Forest Mountain Areas
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, and is particularly harmful to 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 US 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 US Environmental Protection Agency has proposed strengthening the National Ambient Air Quality Standard (NAAQS) for O3. New primary and secondary standard levels have been announced and are expected to be approved in 2014. The EPA has concluded that the primary NAAQS based on an hourly average concentration and used to protect human health is inadequate to protect sensitive ecosystems, and has proposed a new secondary standard that is 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 higher elevation Western ecosystems where little O3 data are available.
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 exist at each site
- Average 8-hr O3 concentrations exceeded the current primary NAAQS of 75 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 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 m), 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.
Forest Service Partners