A.V. AIR HEALTH WARNING ISSUED WILDFIRE, WIND FILL SKY WITH SOOT, SMOKE.

Byline: CHARLES F. BOSTWICK Staff Writer

PALMDALE -- Forest-fire smoke blanketed normally clear Antelope Valley with haze Thursday, pushing air pollution past levels considered harmful by the federal government and prompting school officials to keep youngsters inside at recess and cancel high school football games.

Fine particulates in smoke blowing in from the 17-day-old Day Fire in Ventura County topped more than 130 micrograms per cubic meter in early afternoon, according to monitoring by the Antelope Valley Air Pollution Control District, which issued a health advisory warning people to stay indoors and limit prolonged exertion.

``It's nasty,'' said Tim Azevedo, assistant superintendent for Antelope Valley Union High School District, which canceled outdoor athletic activities Thursday.

In the first health advisory issued for the Antelope Valley since the fire started Sept. 4 in the Los Padres National Forest, air quality officials said individuals with respiratory disease such as asthma should avoid moderate or heavy exertion. Everyone else, especially children and the elderly, should limit prolonged exertion.

Antelope Valley residents were also advised to stay indoors if possible, keep windows and doors closed, and set air conditioners so they do not draw in outside air.

The smoke is expected to be less of a problem today, when Santa Ana winds are expected to push the smoke southwest rather than northeast from the fire, which by Thursday had topped 106,000 acres.

The high school athletic activities canceled Thursday included Lancaster High School's football games against Canyon High School of Santa Clarita. Administrators said they will decide today whether to hold tonight's games.

Palmdale School District administrators advised school officials to keep students and staff members inside as much as possible. Administrators said they have been monitoring air quality since the fire started.

As of early afternoon Thursday, the Antelope Valley's readings were averaging 74 micrograms per cubic meter. Typical Antelope Valley readings are below 20 in the mornings, and 30 to 50 in afternoons, Antelope Valley AQMD operations manager Bret Banks said.

The real-time measurement was 25 micrograms at midafternoon Wednesday, rising to 48 at 10 p.m. as smoke blew in from the fire, records show.

Federal health standards are violated when the 24-hour average for fine particulates tops 35 micrograms per cubic meter -- a 2006 tightening from the former standard of 65 micrograms.

Visibility Thursday was down to 2 1/2 miles in Palmdale, four miles in Lancaster and 12 miles at Edwards Air Force Base, compared with 45 miles at Edwards the day before.

Breathed in, fine particles can reach the deepest regions of the lungs, the EPA says. They can aggravate asthma and lead to premature death in people with heart and lung disease, as well as reduce visibility.

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Photo:

(color) Forest-fire smoke obscures the Palmdale Water District wind turbine and hides Air Force Plant 42 in a view from Vista Point on the Antelope Valley Freeway above Palmdale on Thursday.

Jeff Goldwater/Staff Photographer