Summer breezes blow the Valley's ground-level ozone into the mountains. The air is no worse than it was before. And this is really no different than the ozone alerts you receive in Fresno. Ozone is a corrosive, invisible gas that damages needles and leaves in some Sierra trees. Research shows that mature giant sequoias, which can survive 3,000 years, apparently are not affected, but younger sequoias suffer some damage.
Ozone also irritates the respiratory system in humans.
But the ozone is invisible, and it can be harmful. Ozone already is monitored year-round in Sequoia National Park at Giant Forest and on the road to Mineral King. The Giant Forest monitor will be used to determine air quality for both Sequoia and Kings Canyon parks. The National Park Service last year issued guidelines suggesting health advisories for parks with such monitors. Displays for the smog advisories will be in the Grant Grove, Lodgepole and Foothills visitor centers.