As you live and breathe

IN his 1998 essay “L.A. Glows,” Lawrence Weschler described the “incredible stability” of the air in Southern California, a phenomenon that has everything to do with thermal inversion, the way the mountains trap ocean breezes in the L.A. Basin beneath desert currents from the east. It’s a terrific detail, scientific and yet at the same time cultural, and I couldn’t help remembering while reading David Carle’s “Introduction to Air in California” (University of California Press: 250 pp., $16.95 paper).

The latest volume in the California Natural History Guides series (which also includes Carle’s “Introduction to Water in California”), “Introduction to Air in California” is a book that, in its own way, conflates science and culture as well. Elegantly written, copiously researched and illustrated, this is a Baedeker of the atmosphere, a guide not just to the sky’s corpus but also to its soul.

What is it that defines the air in California? Unfortunately, Carle reminds us, today it’s not so much Weschler’s “uncanny stillness” as the particulates we leave behind. “It ought to be easy to take California’s air for granted,” he writes in the opening lines, before acknowledging the influence of ozone warnings and smog alerts. Such a perspective marks much of the book, especially its history of the state’s 15 different “air basins” -- among them San Diego County, the San Joaquin Valley, Lake Tahoe and the Salton Sea -- and its discussion of emission sources and clean-air programs, including renewable energy resources such as windmills and solar power.

As to why this is important, Carle offers a direct, and highly sobering, point of view. “Although Californians can take pride in the progress made fighting air pollution and in leading the nation to face such challenges,” he writes, “the majority of Californians still breathe air with unhealthy levels of pollutants.... Studies suggest that breathing air in parts of Southern California can reduce one’s life expectancy by more than two years.”

-- David L. Ulin