The famed redwoods of Sequoia National Park are slowly yet surely being replaced by another kind of enduring landmark: a sky-spanning carpet of lung-blistering smog.
Wafting in on an eddy that swirls over the heavily industrialized San Joaquin Valley, the tainted air gives a diseased touch to any plant or human it encounters in the mountains. Because of the perpetual gas-shower of ozone, PCBs and aerosolized fertilizers, Sequoia has the worst air pollution of any national park in the country.
Hikers might cough and hack on days with particularly bad air quality, as high levels of ozone can provoke lesions on the lungs, according to this depressing AP story on the park's environmental woes. Here's the AP's update on how bad it's gotten in the land of the giant redwoods, located just east of Fresno:
"Ozone levels here are comparable to urban settings such as L.A.," said Emily Schrepf of the nonprofit advocacy group the National Park Conservation Association as she beheld the diminished view. "It's just not right."
This is not the place to take in a whiff of fresh mountain air. Smog is so bad that signs in visitors centers caution guests when it's not safe to hike. The government employment website warns job applicants that the workplace is unhealthy. And park workers are schooled every year on the lung and heart damage the pollution can cause.
Wheezing backpackers aside, the pollution is also afflicting the treasured trees, which can be nearly 3,500 years old and are part of a Congressionally mandated, living national shrine. About 90 percent of Jeffrey pines around the Giant Forest show evidence of ozone damage. Their needles are chlorotically mottled and fall out earlier than usual. Such yellowed, balding pines can't draw as much energy from photosynthesis. They become stunted with smaller age rings.
The iconic Sequoias that dot the park like radio antennae seem more resistant to the effects of ozone, created when sunlight frazzles chemicals adrift in the air. However, Sequoia seedlings are "suspected to be more vulnerable to ozone injury," according to the National Park Service, spelling trouble for the future of the species.
Ozone is just one of the pollutants that drifts up into the firs from sprawling farms and truck-clotted highways below. These other nasty substances can also be found in the air around Sequoia:
PCBs: These industrial byproducts have found a home in the serene glens and streams of California's forests. Says the NPS: "Some PCBs have negative effects on animals by imitating specific hormones in concentrations as small as parts per trillion. They can cause changes in wildlife reproductive capacity, longevity, intelligence, and behavior, or can lead to cancer or mutations."
Pesticides: Farmers in the San Joaquin Valley spray out an incredible amount of insect-killing chemicals, 37,000 tons in 2010 alone. Not all of it stays on the ground. Researchers have yet to do a formal study linking California's pesticide use to impaired wildlife in the parks, but the NPS is aware of "circumstantial evidence" that suggests it's happening. This evidence includes the fact that peregrine falcons at Moro Rock have never managed to have babies; their eggshells are thinner, and sometimes whiter and chalkier, than they should be. The park service also is concerned about frogs:
The foothill yellow-legged frog completely disappeared from these parks in the 1970s, and today exists in the Sierra Nevada only in a handful of widely scattered populations along the western foothills. The frog is much more common on the opposite side of the San Joaquin Valley (in the foothills of the Coast Range), upwind from pesticide drift. Synthetic chemical drift may also be playing a role in the ongoing decline in mountain yellow-legged frogs in these parks, though other factors, such as non-native fish introduction to park lakes, are also likely to be important.
On the plus side, all this air pollution does wonders for the region's sunsets. Mike Baird caught this blooming hellscape in the sky from Moro Rock in 2010:
Top 2007 photo of air pollution around Sequoia National Park by Ianqui Doodle.