Officials in Southern California are advising residents to stay indoors and batten down the hatches as wildfire smoke continues to pollute the air.
On Wednesday afternoon, the South Coast Air Quality Management District (AQMD) extended an air quality advisory, citing worsening conditions due to smoke from the Bridge and Line fires. The advisory will remain in effect until at least 11 p.m. local time on Thursday.
The Bridge and Line Fires, currently burning just northeast of Los Angeles since September 8 and 5, respectively, are expected to heavily impact areas including the San Gabriel and San Bernardino Mountains, Big Bear, and Mount Baldy.
"Limit your exposure by remaining indoors with windows and doors closed or seeking alternate shelter," the alert said.
"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. Avoid burning wood in your fireplace or firepit and minimize sources of indoor air pollution such as candles, incense, pan-frying and grilling."
The updated alert recommends that anyone in affected areas who must go outside should do so for as little time as possible and should wear "a properly fit N95 or P100 respirator."
Affected areas could see the Air Quality Index (AQI) reach "unhealthy for sensitive groups" categorization or higher over the course of the day. At such levels, sensitive groups, including children, the elderly, and individuals with preexisting respiratory conditions such as asthma, should avoid prolonged time outdoors, according to AQMD guidance.
"Big Bear is expected to reach the unhealthy for sensitive groups AQI category or higher on Thursday afternoon. Most other smoke-impacted areas are expected to be in the moderate AQI category or higher," the alert said.
As of 2:30 a.m. local time on Thursday, the Bridge Fire, which is burning in the San Gabriel Mountains between Piñon Hills, Mount Baldy, La Verne and Crystal Lake, had scorched 54,795 acres and was 41 percent contained.
Meanwhile, the Line Fire—burning between Highland, Running Springs, Big Bear Lake and Angelus Oaks—had burned 39,232 acres and was 51 percent contained.
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.
Cooler temperatures and higher humidity over the past few days have lowered fire activity, supporting fire-suppression efforts, the U.S. Interagency Wildland Fire Air Quality Response Program said in its "Smoke Outlook" on Wednesday.
As a result, smoke is expected to decrease over the coming days, with an "expected improvement in air quality on Friday-Saturday with wind shift to transport smoke to areas south of Bridge Fire area."
The AQI level is expected to stay at moderate levels over the coming days, meaning particularly sensitive individuals should consider limiting prolonged or heavy exertion.
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