In the News

Air Quality Affects Our Health the Lake’s Health
date posted: March 2 2004

By John Cobourn, Water Resource Specialist; and Heather Segale, Environmental Education Coordinator; University of Nevada Cooperative Extension

In addition to protecting the water quality of Lake Tahoe, scientists work hard to protect Lake Tahoe’s air quality. The Tahoe Regional Planning Agency (TRPA) works with other agencies to reduce air pollution in order to meet federal, state, and TRPA standards. While these standards help protect human health and vegetation, they also help protect the lake’s water quality. Past research has shown that half or more of the nitrogen and a third of the phosphorus in the lake may come from the air. These nutrients, along with dust, smoke and exhaust particles falling out of the air, are major contributors to the steady loss of the lake’s world famous water clarity.

Current air pollution research involves many researchers and uses expensive and sophisticated instruments. There are eight continuous air quality and weather monitoring stations around the lake. TRPA is a major partner in a multi-agency air quality study, the “Lake Tahoe Atmospheric Deposition Study,” led by the California Air Resources Board. This study will provide additional data needed to better determine the sources of air pollution and their relative importance for both air and water pollution. It will also provide information to help TRPA determine the best control strategies for the update of their 2007 Regional Plan. In addition, TRPA recently paid for research performed by the University of California, Davis and Air Resource Specialists, that examines the impact of several potential air quality pollutants on the lake’s water quality. These factors include roadway dust resuspended by traffic, vehicle exhaust from both unleaded-fuel and diesel-fuel engines, and wood smoke. Results from these studies will be posted on the TIIMS Web site, www.tiims.org, as they become available.

While the air quality at Lake Tahoe is generally quite good, our local bowl-shaped geography makes the Tahoe Basin more sensitive to air pollutants than in other areas. Winter weather conditions often cause smoke and other air pollution to accumulate close to the ground overnight. This is due to temperature inversions that trap air at the surface. Historical measurements indicate that the main sources of winter air pollution in the Basin are local vehicle use, from both exhaust and road dust, and wood smoke emissions from fireplaces and wood-burning stoves.

In the summer, air pollution in the basin originates from both local and out-of-area sources. Air pollution from nearby cities, such as Sacramento and San Francisco, is carried into the Tahoe Basin by the wind. Vehicle use is the main cause of the locally generated air pollution in the summer. One way to reduce the air and water quality problems caused by automobiles is to limit the use of personal vehicles. Residents and visitors can walk, ride a bike, or use public transportation to cut down on personal vehicle use. With some planning, several errands can be done with one trip. Other ways to help include learning more about air pollution and vehicle use in the basin and paying attention to these issues when it comes time to elect local, state and national officials.

Prescribed fire or controlled burns are another source of air pollution common in spring, late fall and winter. Prescribed fire is used to help reduce the unnatural amounts of hazardous fuel in our forests. This management tool is necessary in order to protect communities from catastrophic wildfires, which not only threaten homes and lives, but also result in extreme amounts of air pollution for weeks or months at a time. Prescribed fires are also needed to promote healthier forest conditions. To minimize the impacts to air quality, all controlled burns require extensive planning months to years ahead of time, occur only after handwork to prepare the fuels has been completed, and are conducted only when weather conditions are deemed appropriate (Air-Resources-Board-approved “burn days”). In the long term, fuel-reduction efforts actually protect air and water quality by preventing large, out-of-control fires that “smoke out” the basin for prolonged periods.

The heating of homes through wood burning is a significant source of Tahoe’s air pollution during the colder months. Most wood-burning stoves and fireplaces release far more air pollution, indoors and out, than heat sources using natural gas and other efficient fuels. Therefore, air pollution can be reduced by replacing old wood-burning stoves with clean-burning gas fireplaces; new wood, pellet or gas stoves; or inserts. When purchasing a new stove, look for EPA-approved models, which have higher heating efficiency and therefore produce more heat and less pollution. Old wood-burning stoves can waste 30 percent to 60 percent of your wood.

To reduce the amount of wood smoke produced in the basin and promote higher-efficiency heating technology, the TRPA’s Code of Ordinances addresses this issue. It includes maximum emission limits for all new wood heaters installed in the basin, and requires the removal of older, nonconforming wood stoves when real estate is sold or transferred. Since the adoption of this program, wood smoke levels have been reduced during the winter. For more information about preventing air pollution, contact Jennifer Quashnick, Tahoe Regional Planning Agency, (775) 588-4547 Ext. 278, or visit www.trpa.org/ordinances/pdffiles/code91.pdf.

Watch for “The Lake Tahoe Report” on KOLO-TV News Channel 8 every Tuesday at 5 p.m. to learn more. Next week learn about transportation and traffic issues in the Tahoe Basin. “The Lake Tahoe Report” is a collaborative effort of the Lake Tahoe Environmental Education Coalition, University of Nevada Cooperative Extension, UC Davis and the USDA Forest Service. For more information, contact Heather Segale, University of Nevada Cooperative Extension, (775) 832-4138, or logon to www.lteec.org or www.unce.unr.edu.