Officials in Southern California are advising residents to stay indoors and take action to reduce windblown dust that's set to diminish air quality in the region throughout Friday and into Saturday morning.

On Thursday afternoon, the South Coast Air Quality Management District (AQMD) issued a windblown dust advisory for the Coachella Valley area, as gusts of up to 30 miles an hour are expected to kick up particulate matter into the air. The advisory was issued at 5:30 p.m. local time on Thursday and will remain in place until 6 a.m. on Saturday.

"Windblown dust is expected to cause Air Quality Index (AQI) values to reach Unhealthy for Sensitive Groups or worse in the Coachella Valley on Thursday and Friday nights," the AQMD said in its statement.

"Limit your exposure by remaining indoors with windows and doors closed or seeking alternate shelter. Avoid vigorous physical activity. Run your air conditioning and/or an air purifier. If possible, do not use swamp coolers or whole house fans that bring in outside air."

The AQMD also cautioned drivers, advising them to slow "down if driving on dirt roads" and to "help minimize dust pollution by stabilizing loose soils."

A car driving along a dusty road. Air quality in Southern California is expected to be poor due to windblown dust and ash, with officials advising residents to drive slower on dirt roads to prevent... A car driving along a dusty road. Air quality in Southern California is expected to be poor due to windblown dust and ash, with officials advising residents to drive slower on dirt roads to prevent kicking up more particulate matter. Boogich/Getty

Potentially impacted areas include the Coachella Valley and Riverside County, southeast of Los Angeles.

Under an "Unhealthy for Sensitive Groups" advisory, the following groups should limit prolonged exposure or heavy outdoor exertion: People with heart disease, pregnant women, children and older adults, and people with lung disease, such as asthma.

The warning comes after days of poor air quality in the region, as authorities have battled to contain the Bridge and Line Fires burning to the northeast of Los Angeles.

The smoke advisory issued earlier in the week has been extended several times and will remain in place until at least 11 p.m. local time on Friday.

According to the National Interagency Fire Center, both fires are threatening numerous structures, as well as communication and energy infrastructure. Evacuations and road and trail closures are in effect close to the fires.

As of 8:47 p.m. on Thursday, the bridge fire had scorched more than 54,000 acres of land, destroying 81 structures. The Line Fire now covers over 39,000 acres and is still 53 percent contained.

Ash from the fires will combine with dust, amplifying the effects on air quality. Residents should expect AQI levels to vary over time depending on wind speed and direction.

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