Garnet Fire sends dense smoke across California and Nevada; Yosemite air briefly 'hazardous'

The Garnet Fire has burned more than 56,000 acres in the Sierra National Forest northeast of Fresno, California, and prompted Dense Smoke Advisories for parts of Central California and western Nevada as firefighters work to increase containment and protect groves of giant sequoias.

Ignited by lightning on Aug. 24, the fire was 15% contained as of Tuesday evening, officials said. Crews reported making “significant progress” holding the most troublesome sections to containment lines, while also funneling resources to defend McKinley Grove, where some sequoias exceed 230 feet in height.

Large smoke plumes from the blaze reduced visibility and degraded air quality across a wide area. Yosemite National Park recorded “hazardous” air quality on Monday — the worst rating on air quality scales — and had improved to an “unhealthy” rating by Tuesday evening, park officials said. The National Weather Service office in Hanford, California, issued a Dense Smoke Advisory covering portions of both states, warning that smoke could reduce visibility to a mile or less at times and create hazardous conditions for drivers.

Hawthorne, Nevada, was reported under “unhealthy” air quality conditions, while more distant communities such as Esmeralda County, Nevada, reported air unsafe for sensitive groups. Officials cautioned that air quality was unlikely to improve until winds shifted or firefighters increased containment.

The U.S. Environmental Protection Agency described how intense wildfire heat drives smoke high into the atmosphere, where it cools and later descends, spreading and diluting but sometimes concentrating pollutants at ground level. “As smoke moves downward to ground level, it becomes more diluted and often more widespread,” the agency said.

Public health officials noted the immediate respiratory risks. Air characterized as “hazardous” can harm even healthy individuals and poses heightened danger to people with respiratory illnesses. The National Weather Service cited studies estimating that poor air quality contributes to more than 100,000 premature deaths in the United States each year.

Fire crews continued a mix of direct and indirect suppression tactics, including building containment lines and conducting structure protection where homes and infrastructure are threatened. Incident commanders focused on holding existing lines while conducting point protection for McKinley Grove, home to the grove’s tallest sequoias and cultural resources.

Officials urged residents in affected counties to monitor local air quality alerts, limit outdoor activity when smoke is present, and take precautions while driving in areas of reduced visibility. The National Weather Service and local public health agencies advised that conditions could change quickly depending on weather and fire behavior.

Fire managers provided regular updates on containment and resource assignments and said more personnel and equipment remained committed to the incident. As crews press to gain additional containment, officials said the primary objectives are to protect life, property and sensitive natural resources while working to reduce smoke impacts to nearby communities and national parklands.