Wildfires causing unhealthy air in Northern California

A thick pall of smoke continued to hang over much of Northern California on Tuesday as scores of lightning-sparked wildfires marched across 76,000 acres.

Air quality officials warned residents to stay indoors as the smoke from fires from Monterey County to the Oregon border turned the sun into a pale orange disc.

Youth soccer teams canceled practices, golf dates were skipped, and a few watchful folks even donned surgical masks before venturing outside.

Regulators said it was the worst air to hit the region in years. Air quality is considered satisfactory when the Air Quality Index is below 100.

In Butte County, smoke cascading downhill from nearby fires sent the index rocketing toward 205, surpassing the threshold for “very unhealthy” air.

The index topped out at 210 in some parts of Sacramento County, and officials issued warnings to curtail outdoor activities even after it slipped lower late Tuesday.

Further south in San Joaquin County, the smoky air hit 155 on the index.

Even normally breezy San Francisco drooped for a second day under a haze spread by smoldering wildfires in Napa and Fairfield, and authorities issued a smoke advisory there.

Despite the eerie conditions, firefighters continued to make headway against the fires, which began Saturday when a rare onslaught of dry lightning hit scattered spots all over the northern part of the state, igniting more than 800 blazes.

Most of the fires were being fought away from populated areas, but a blaze near Big Sur destroyed or damaged 16 homes and two adjacent structures.

The 8,500-acre fire is one of two bedeviling the Los Padres National Forest. A wildfire that started earlier this month is 66% contained but has charred about 60,000 outback acres.

Meanwhile, firefighters were making progress against fires in Napa and Shasta counties, while blazes in Santa Cruz and San Benito counties have been fully contained.

 eric.bailey@latimes.com