Wind shift, firefighting efforts relieve smoke-choked locals.
Mono County residents were breathing a little easier this week as winds shifted and firefighters stepped up their on-the-ground efforts to battle the Rough Fire in the Sierra National Forest near Kings Canyon.
As of Thursday morning, the lightning-caused fire had grown to almost 56,000 acres. Containment grew too, from the single digits last week to 25 percent, with 2,152 firefighters responding, including 24 crews, 153 engines, and 11 helicopters.
Last week the Mono County Public Health Department issued a Stage 1 Health Advisory after smoke from the Rough Fire inundated the County. Under Stage 1 the Health Department advised children, the elderly, people with heart or lung problems, or people with current illnesses such as the flu, to stay indoors and avoid strenuous outdoor activities in the impacted areas.
As Public Health Officer Dr. Rick Johnson explained, Stage 1 means the PM-2.5 (particles less than or equal to 2.5 micrometers in diameter) level exceeded 100 micrograms per cubic meter of air (µg/m3).
Residents of this area might be more familiar with the term PM-10: “PM-10 is what you see when the Owens Lake or Mono Lake dust is kicked up by the wind,” Dr. Johnson explained. In the case of Owens Lake, a Stage 1 Alert is sent out at a PM-10 level of 400, “which happens frequently,” Dr. Johnson said.
But the main hazard with wildfire smoke is smaller PM-2.5 particles.
“Because of the smaller size, these particles penetrate deeper into the lungs, going down into the smallest airways and the air sacs—alveoli—which is where oxygen is exchanged between the air and blood,” Dr. Johnson explained. “The particles and the inflammation or swelling that they cause interfere with the body’s ability to get oxygen efficiently.”
As of this week, Mono County is no longer in a Health Alert stage, “although that changes hour by hour with the wind,” Dr. Johnson said. Bishop has also seen a significant decrease in both PM-2.5 and PM-10 levels, from a high of close to 80 earlier this week to about 40 µg/m3 as of Wednesday afternoon, according to the Great Basin Unified Air Pollution Control District website. Olancha saw a spike in PM-10 to about 120 µg/m3 Tuesday evening, but has since declined to about 30-40, as has Lone Pine.
Dr. Johnson said he thought it was unlikely the Rough Fire would lead to a Stage 2 advisory. The worst Mono County has ever experience was a Stage 4 Advisory two years ago during the Rim Fire.
The Rough Fire, which began on July 31, is only a fraction of the Rim Fire’s size (the Rim Fire eventually grew to about 257,000 acres), and better weather this past weekend allowed firefighters to begin more aggressive efforts on the ground.
According to the California Smoke Information website, crews are currently conducting perimeter control, connecting fire lines down to Kings River and from Cherry Gap to McKenzie Ridge. Hand and aerial firing will likely continue over the next several days on the northern zone of the fire to keep the fire backing to the north fork of the King’s River.
According to Rough Fire Public Information Officer Bob Kurilla, the dramatic reduction in smoke in both Mono and Inyo Counties is the result of these increased firefighting efforts.
“Less smoke is being generated now as things are getting mopped up and contained,” he said. “The most fire activity today [Tuesday] is up in the northwest around Wishon Reservoir.”
Kurilla also dispelled rumors that the Sierra National Forest would simply back off and let the fire burn. “The fire is being actively suppressed,” he said. He added that crews are coming from all over California, as well as from out of state, to help with firefighting efforts.
The fire’s InciWeb site notes that “The rugged terrain of Southern California’s Rough Fire provides numerous hazards for wildland firefighters. Steep mountains, rolling rocks, and hazard trees make for a dangerous job among the already treacherous risk involved on a fire.”
The site projects that the high-pressure over the West Coast will shortly break down, “allowing for a gradual cool down along with improving overnight recoveries through weekend and into early next week.”