Bay Area air pollution reaches Devils Postpile National Monument

Air samples were taken at Devils Postpile National Monument, near the crest of the Sierra Nevada, southeast of Yosemite National Park.
(National Park Service)

That fresh, pine-scented mountain air that you happily breathe in the Sierra Nevada could be hazardous to your health.

Samples taken by federal scientists in Devils Postpile National Monument, southeast of Yosemite National Park, show that ozone levels occassionally exceed state air pollution standards.

“Even at remote eastern Sierra locations, ozone air pollution may be a problem for human and ecosystem health,” said Andrzej Bytnerowicz, a U.S. Forest Service research ecologist and lead author of a study recently published in the journal Atmospheric Environment.

Researchers sampled the air at Soda Springs Meadow, elevation 6,918 feet, during the summers of 2008 and 2007. Though the testing found less air pollution than has been documented in portions of the western Sierra, emissions from widespread wildfires in 2008 and urban pollution blown from the Bay Area and the Central Valley elevated ozone levels on some days.


The highest ozone measurements were taken on days when low-altitude air masses originated in the Bay Area and swept across the Central Valley from the northwest.

In June 2007, ozone exceeded state standards on 5 out of 6 consecutive days. In June 2008, high ozone marks were registered when smoke from more than 2,000 lightning-sparked wildfires blanketed much of Northern and Central California.

In general, ozone concentrations were low at night and rose during the day, peaking about 5 p.m.

The study concluded that high ozone levels in the monument area could potentially harm local plants, including sensitive species such as Ponderosa and Jeffrey pines.