FRESNO, Calif. — Amid the pines and incense cedar in Sequoia National Park, the five o’clock rush hour often is limited to squirrels, mule deer and the occasional skunk crossing the road.
Visitors see spectacular 13,000-foot peaks, the largest trees on the planet and far fewer idling cars than at Yosemite National Park.
So the downside here seems unbelievable: Sequoia’s Ash Mountain entrance this year was the worst smog trap in the country.
Worse than Fresno, Bakersfield, Los Angeles, Houston, Atlanta or any other city. With 87 days above the federal eight-hour ozone standard, the foothill entrance was in a smog cloud all summer long.
“People looking for a clean-air vacation are safer going to Los Angeles than Sequoia National Park,” says Kevin Hall, executive director of the activist Central Valley Air Quality Coalition.
But there are no special measures being taken by federal, state and local air-quality officials to clear up Sequoia’s problem. Officials say the bad air will subside as the San Joaquin Valley is cleaned up.
That’s because Sequoia does not create much air pollution. Yet, giant sequoia seedlings and other trees are damaged, and chemicals from the bad air appear in pristine mountain streams, federal scientists say.
So, what’s going on?
Sequoia gets plumes of ozone-making gases when some of the Valley’s air pollution ascends and drifts for miles, mixing with the air at about the same elevation as the Ash Mountain entrance — 1,700 feet. The lung-corroding pollution ranges far from cities and freeways.
And there’s another air-quality problem in Sequoia that almost defies logic. Ozone stubbornly hangs around overnight at isolated foothill sites. The reason: There is too little traffic.
Emissions from overnight traffic actually destroy ozone in darkness, scientists say. So city traffic wipes out a lot of ozone each night in summer.
But foothill and mountain traffic drops off steeply at night. Ozone gases sometimes remain for days.
The same thing happens at Crestline in the San Bernardino Mountains, downwind of the massive Los Angeles metropolitan area. The resort is notorious for having more violations than any other place in Southern California. Many years, it is the worst hot spot in the nation, but not this year.
Crestline had 85 violations of the eight-hour standard—a daylong measurement of ozone. With its 87 violations, Ash Mountain in Sequoia eclipsed Crestline for the first time since 2004.
Sequoia, which is part of the San Joaquin Valley Air Pollution Control District, also was affected this summer by the Lion fire, air officials said. The fire began with a lightning strike July 8 and burned 20,500 acres by mid-August in a neighboring section of the southern Sierra Nevada. Fires create ozone-making gases.
On 16 days this year, the only ozone violations in the Valley air district were at Sequoia, said Seyed Sadredin, executive director of the Valley air district.