Wildfire smoke hovers, then clears, over Southern California. Expect more of the same Friday

Smoke from multiple wildfires hung over much of Southern California on Thursday, blanketing the region with hazy brown vistas and pungent, ashy air and prompting health warnings from air quality officials.

Because of morning wind patterns, some of the highest levels of fine-particle pollution, or wildfire soot, hovered over a coastal area that normally has relatively clean air — the communities that stretch from Santa Monica to Long Beach. That changed later in the day.

The South Coast Air Quality Management District issued a smoke advisory spanning much of Los Angeles, Orange, Riverside and San Bernardino counties. Officials predicted smoke and ash to produce pollution levels that are “unhealthy for sensitive groups,” including children, the elderly and people with preexisting health problems. Air pollution could potentially reach higher levels in areas directly downwind from fires, the advisory noted.

Among the areas where officials expect poor air quality through Friday morning:

• Pacific Palisades, Santa Monica and the Westside of Los Angeles
• Riverside, Jurupa Valley, Mira Loma, Corona and the Chino Valley
• San Bernardino, Muscoy, Rialto, Colton, Highland and communities along the 215 Freeway corridor

Air quality in the “moderate” range was widespread Thursday morning as winds blew from the north and northeast, pushing smoke south and southwest across Los Angeles County. Pollution reached levels that are “unhealthy for sensitive groups” along parts of the coast, including Long Beach and the South Bay.

But with winds predicted to shift to come from the west and southwest Thursday afternoon until sunset, the smoke could move back east and northeast across the Los Angeles Basin.

Elevated pollution levels are expected again in the early morning hours Friday.

Pollution tends to be worst in the early morning, when weather conditions cause wildfire smoke to hug close to the ground. Webcam imagery showed smoke from the Hill and 46 fires hovering near the ground in the Riverside and Chino Valley areas Thursday morning, according to the air district.

Wildfire smoke can irritate the eyes, nose and throat, trigger asthma attacks and raise the risk of heart attacks and stroke. Tiny, harmful particles in the smoke can lodge deep in the lungs and pose serious health risks, especially to children, the elderly and people with lung diseases.

The district updates air quality conditions, maps and pollution readings hourly online.