KETCHUM - Even with more manpower arriving to fight the Castle Rock Fire, residents of Ketchum aren't breathing easier.

Cooler weather on Thursday, along with the arrival of an additional 400 firefighters - bringing the total to almost 1,000 - provided some long-awaited relief for the Wood River Valley. But the sights and smells of the fire were inescapable as pillars of smoke loomed over the Warm Springs area, and a health warning was issued Thursday by the state Department of Environmental Quality.

The Castle Rock Fire, which started with lightning strikes on Aug. 16, grew to 16,070 acres Thursday and was only 9 percent contained according to fire incident teams and the U.S. Forest Service. More than 50 fire engines and 10 helicopters are at work on structure and property protection.

Crews said progress was continuing on burn out operations that started Wednesday in the Hulen Meadows areas. The burns were expected to move north and last into Thursday evening.

Additional burn out operations started on the north side of Griffin Butte with the use of aerial drops from helicopters, while other preventive burns in Fox Creek and the Warm Springs drainage also started on Thursday.

"The controlled burning, which took place inside the fire lines, was very successful today," Robert Beanblossom, an incident spokesman, said Thursday. However, he said the fire progressed east toward Ketchum and Sun Valley, though he did not know by how many acres Thursday night.

The burns created heavy pillars of smoke in the Warm Springs area, further soiling air quality in the Wood River Valley. DEQ issued an air advisory of "unhealthy for sensitive groups" due to wildfire smoke.

"The recommendation is to try to get away from the smoke," said Steve VanZandt, an air quality science officer for the Idaho Department of Environmental Quality. "Stay indoors, and if you have a filter, use a filter."

The warning comes after the fire district issued a ban on burns in Blaine County. That ban remains in effect for the Wood River Valley.

The warning is for everyone - healthy people, and especially those who suffer from chronic pulmonary problems.

While VanZandt said the department is not specifically telling people to leave the area, it strongly recommends that residents at least "use their own senses" to avoid smoke and maximize their time spent indoors.

"It's very irritating to the respiratory tract," VanZandt said. "Normal people feel it in (their) lungs and chest. My eyes burn. I feel it in my throat."

People who suffer from asthma face a higher risk of attack. The smoke also escalates the risk for those suffering from cardio-pulmonary problems. And the smoke can certainly aggravate sinus problems, he said.

Pockets of fair air quality abound in various parts of the valley. Some joggers are able to continue their outdoor activities by knowing where to run. But be vigilant, because the winds shift the smoke at different times of day.

Attention now turns to the weekend as the National Weather Service predicted cool but gusting weather over the next three days. Friday's outlook called for mostly sunny skies, highs near 67, and winds to the northwest at 9 to 16 mph turning southwest. Wind gusts could go as high as 24 mph.

Fire incident teams are planning another public meeting with local residents tonight at 6:30 at Hemingway Elementary School.

Times-News writer David Cooper and the Wood River Journal contributed to this report.