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As the Bobcat Fire burns for the twelfth day, Los Angeles County officials warned that air quality will reach “very unhealthy” levels in areas near the massive inferno on Thursday.

Smoke from the Bobcat and El Dorado fires will again create poor air quality throughout Southern California, according to the South Coast Air Quality Management District forecast.

The stubborn blazes have been burning for nearly two weeks now, and while firefighters have gained the upper hand over the El Dorado Fire, containment of the 79-square-mile Bobcat Fire remained at just 3% as of Thursday morning.

And though air quality somewhat improved Wednesday — the index was “moderate” in central Los Angeles, when it was previously “unhealthy” — L.A. County on Thursday again extended a smoke advisory that has been in effect for more than a week.

According to the county’s Department of Public Health, air quality will be “very unhealthy” for everyone in the eastern San Gabriel Valley, the Pomona/Walnut Valley and the San Gabriel Mountains — areas closest to the Bobcat Fire, which is burning in the Angeles National Forest.

People in those parts are urged to move outdoor activities inside or reschedule them altogether, and should avoid prolonged or strenuous exertion, said Dr. Muntu David, the county’s health officer. Additionally, people who are sensitive to air pollution, as well as individuals with conditions such as heart or lung disease, shouldn’t partake in any physical activity outside and are encouraged to stay indoors as much as possible.

The following parts of the county will experience unhealthy air quality: central L.A. County; south central L.A. County; northwest coastal L.A. County; southwest L.A. County; southeast L.A. County; south coastal L.A. County: east San Fernando Valley; west San Fernando Valley; west San Gabriel Valley; south San Gabriel Valley; and the Antelope Valley.

Anyone living or working in those areas are encouraged by health officials to minimize physical activities outdoors; those with sensitive conditions should stay inside as much as possible.

The Santa Clarita Valley, meanwhile, will experience air quality that is unhealthy for individuals with sensitive conditions, and people there are also advised to keep outdoors activity brief and try not to overexert themselves.

Health officials are also telling everyone in areas impacted by smoke to watch for symptoms of poor air quality, which can include coughing, wheezing, shortness of breath or difficulty breathing, chest tightness, or discomfort with deep breaths of physical activity.

Anyone who experiences symptoms should stop all activity, go inside or use medication, if prescribed. If the symptoms don’t get better with those measures, seek medical attention, health officials said.