Already this year, ozone levels in Sequoia National Park have exceeded federal health standards (being comparable to those found in Los Angeles), and the air quality is only going to get worse throughout the summer, according to a new Associated Press report. Hikers and visitors—as well as residents and park workers—are advised to take caution and heed warning signs about daily pollution levels, with health effects ranging from asthma irritation to lung and heart damage that can occur with prolonged exposure. (You can check the air quality online before you go.)
“On a day it’s unhealthy, we ask people if you’re going to do a rigorous hike, we recommend early morning,” Annie Esperanza, a park scientist who has studied air quality in the park for 30 years, told the AP. “It’s quite telling, and it’s very sad.”
But humans aren’t the only ones at risk. The Sequoia redwoods that give the national park its namesake have occupied regions of California for more than 3,000 years, but high levels of ozone have been found to weaken their ability to photosynthesize, making them even more susceptible to threats such as pests and drought.
Two major culprits behind the area's unusually high ozone levels include two of California’s busiest trucking highways and a booming dairy and farm industry just to the west in the San Joaquin Valley. Sequoia NP is perched on the eastern slopes of the San Joaquin basin, where it gives way to the Sierras. It's a beautiful location, to be sure, but when high-pressure systems roll in, they act in concert with the mountains to trap the smog inside.
During last year’s June-to-September summer season, the park violated the National Air Quality standard over 87 times, which made it the most polluted national park in the nation.
Above photo courtesy of Mike Baird at flickr.bairdphotos.com