Sources of Air Quality in the Lake Tahoe Basin Analyzed
In the summer of 2010, Forest Service scientists conducted a study in the Lake Tahoe Basin to address the distribution of ozone in time and space and that of its chemical precursors, volatile organic compounds, and nitrogen oxides. The scientists selected 34 air-quality monitoring sites at different elevations inside and out of the basin. They used passive samplers to determine the concentrations of volatile organic compounds, nitrous oxides including the common pollutant nitrous dioxide, and ozone. Real-time ozone monitors at a subset of 10 sites were used to evaluate changes of this pollutant during a 24-hour period.
The scientists determined that high concentrations of ozone found on the western slope of the Sierra Nevada are caused by air-pollution emissions from the California Central Valley, which rarely get into the Lake Tahoe Basin. Elevated ozone concentrations on the eastern side of the basin at the high-elevation sites indicated the ozone likely originated from local emission sources. High-ozone concentrations in the middle of Lake Tahoe most likely originate from powerboat emissions and the high intensity of photochemical processes taking place at that location. The research results will help land managers and community leaders develop strategies to improve air quality in the Lake Tahoe Basin.