Southern California fire weather expected to linger. What does that mean for air quality?

With fires still raging around Los Angeles and high winds expected to last through Friday, it's not clear when air quality in the region will improve, local experts said Thursday.

The time it will take for smoke from wildfires burning around Los Angeles to dissipate is a moving target. Much of Los Angeles County is still experiencing unhealthy air due to smoke from the Palisades, Eaton and Hurst fires that have collectively burned over 29,000 acres, according to Cal Fire. All have little or no containment at this point. They've been aided by the notorious Santa Ana winds.

“As long as these fires are burning, there’s just a ton of smoke in the air right now,” Sarah Rees, deputy executive officer for planning and rules at the South Coast Air Quality Management District, a local regulatory agency, told USA TODAY. “It's going to continue to cause these hazardous air quality conditions.”

Advisories for smoke, dust from burned areas

The air quality district has issued advisories through at least Thursday evening due to smoke and windblown dust from burned areas. The advisories extend far beyond the areas directly engulfed in flames.

The winds have somewhat slowed, but that means the smoke will spread more, extending eastward, to parts of San Bernardino County, and south to Orange County. Both counties are highly populated. The greater Los Angeles region, with a population of over 18 million people, already has some of the worst air quality in the nation.

“In the greater LA area, we’re experiencing levels of air quality that are unhealthy for everybody,” Rees said.

Smoke from the wildfires — which burns vegetation but also homes, cars and other manmade materials — is toxic to breathe in because of tiny particles and gases that enter the lungs and bloodstream. These particles can immediately trigger an asthma attack in vulnerable people and increase risks of other lung problems and heart attacks. Longer term, they pose an increased risk of cancer and dementia, studies show.

Everyone is at some risk from this pollution, experts said, but those at highest risk include young children, older adults, and those who are pregnant, have heart or lung conditions or weakened immune systems.

No one knows what's in the air

More is known about the health effects of breathing air from burning trees and brush in wildfires, according to Keith Bein, a professional researcher at the Air Quality Research Center, at the University of California, Davis. Less is known about the effects of burnt synthetic materials, in the cases of homes and cars, such as in Pacific Palisades or Altadena.

Examples of what’s called “wildland urban interface” fires, where residential areas and wilderness meet, began occurring in Northern California in 2017, with the Santa Rosa fire, which destroyed an entire neighborhood, and the 2018 Camp fire, which razed the town of Paradise. The chemicals released, which can themselves form compounds, often weren’t measured or detected before, Bein said.

The effects from acute exposure, with days of wildfires, aren’t known. It’s also unclear how this affects communities in and around Los Angeles.

“These fires are not that large in terms of California wildfires, but it’s just so densely populated that public exposure impact is really high,” Bein said.

The “cherry on top,” he added, is that the fires are burning structures, consumer products and other materials. This changes the physical and chemical composition of the air pollution.

Over the long term, it’s also unclear how these contaminants may present in soil, water or even inside nearby homes that haven’t burned.

After the fires get under control, wind could help push some particles out of the air, as will gravity with some larger compounds. Gases and fine particles could hang around longer.

Wildfire smoke safety tips: How to keep you, your family and beloved pets safe

In burned areas, winds or movement from the cleanup could kick up contaminated soil, putting them back in the air.

For now, officials recommend people look for air quality levels and try to limit exposure outdoors. Inside, people should keep the air as clean as possible, by keeping windows closed and using air filters and air conditioners that don't draw in unfiltered air directly from outside.

This article originally appeared on USA TODAY: LA fire weather to persist as concerns mount for air quality