Air quality in Tahoe up and down

"South Lake Tahoe is the only city in the state that I know of that has had (on average) an increase in ozone every year for the past 20 years," said Tom Cahill, a professor of atmospheric sciences and physics at the University of California at Davis.

"For most cities it has gone down, and gone down a lot. When it comes to air quality in the Tahoe Basin, we are both winning and losing," he added.

While ozone is up, he said that carbon monoxide and nitrogen oxides are way down, and lead is practically nonexistent. That's due mainly to fuel improvements, catalytic converters and other changes in automobiles.

The ozone layer absorbs harmful ultraviolet sunlight, but high levels can be toxic and can damage the tissue of plants and animals. It's already hurting some trees in the Tahoe basin, Cahill said.

Officials with the California Air Resources Board say the ozone levels are still below allowable limits. The U.S. Environmental Protection Agency has set the allowed ozone level at 0.12 parts per million.

CARB spokesman Jerry Martin said high readings in 1995 hit 0.09, up from a high of 0.08 a year earlier, adding, "Even though it may be rising, even today it is still below the standard."

Cahill said Sierra foothill commuters are a big source of the problem.

"All that stop-and-go traffic on Highway 50, it is just a terrible polluter," he said. "All that raw material goes into the air, and it blows straight up to Tahoe. Give (pollution) a couple hours to cook in the sunlight, and then it's at Tahoe."

He said ways to reduce the pollution include light rail public transportation, car pooling and a cutback in diesel buses.

Also on the rise in the Tahoe Basin is both regional and local haze, Cahill added.

Local haze is caused mostly by wood stoves. Regional haze comes from Sacramento and the San Francisco Bay area. It's a combination of sulfates, organic matter, nitrates, soil and soot.

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