Smoke affects air, entities in Tahoe area
September 4, 2013
Smoke billowing in from the Rim Fire, which is burning near Sonora by the Yosemite National Park area, has enveloped the Lake Tahoe and surrounding area, causing air quality to decline.
The Lake Tahoe area was upgraded Tuesday from the “unhealthy for sensitive groups” category to “unhealthy” air quality, according to the El Dorado County Air Quality Management District. The air quality index was reported by officials to be 181, the upper end of the unhealthy designation.
The Nevada Division of Environmental Protection air quality monitors in Gardnerville and Carson City indicated the area will continue to see “unhealthy” and “very unhealthy” conditions throughout the week, a news release from the county stated.
The wildfire, which began Aug. 17, had grown to 179,481 acres by Tuesday. The fire had grown 50,000 acres in 24 hours at one point, according to figures from Inciweb.org, a federal incident website.
Smoke intensifies health risks
Barton Memorial Hospital officials reported respiratory complaints have surged compared to typical trends this time of year.
Officials reported complaints have quadrupled from the typical number of emergency-room patients.
People who are most vulnerable to the smoke usually have chronic respiratory problems, “such as asthma and COPD or chronic obstructive pulmonary disease,” an email from NDEP stated.
An NDEP news release advised people to stay indoors with the windows and doors closed, and health officials said keeping the air conditioner on with recirculated air can be beneficial. Strenuous exercise or work outdoors is discouraged, and people are advised to drink lots of fluids, the release stated.
Fire departments rally against blaze
Lake Valley Fire Protection District, South Lake Tahoe Fire Department, Fallen Leaf Lake Fire Department and more agencies have sent resources to help with the Rim Fire effort, according to Lake Valley Fire Protection District spokeswoman Leona Allen.
Officials said the Rim Fire’s behavior is difficult to predict because of its location in areas that are not navigable by vehicle and the abundant dry fire fuels.
“The biggest (problem) is the terrain,” LVFPD Chief Gareth Harris said from the South Lake Tahoe Office. “It’s inaccessible. There’s very little in the way of roads or paths.”
Because of the extreme terrain, the firefighters have had to fight on foot without the assistance of additional water sources, Harris said.
Prevailing winds moving southwest coupled with dry fuels and high temperatures have been critical factors in the fire’s growth and smoke dissemination. If the winds were to move back northbound, Harris said, it could push the fire back at itself, slowing it down.
“There’s so much heat being released from the fire, it creates a convective column that creates almost a vacuum under it,” Harris said. “It’s creating its own winds. It takes the moisture out of the air with all that heat.”
Harris said many portions of the fire zone have not burned in many years, making it easier for the fire to spread. There also has been low humidity in the area.
With large 75- to 100-foot trees being burned hottest at the tops, called a “crown fire,” flames move quickly overhead with winds carrying embers around the firefighters.
When that happens, Harrison said, it can trap firefighters if the blaze passes over them behind the line.
“Firefighting is a business of risk management,” Harris said. “There’s nothing worth dying for out there. We’ve even had base camps burn.”
The chief said the best way to avoid getting trapped is to adequately identify escape routes and keep communication lines open.
“The reality is there are no natural fire breaks, and it’s really going take Mother Nature changing her mind and changing weather conditions,” Harris said, adding he does not want to make a prediction about the fire at this time, but he does expect it to continue until weather conditions change. “If we get some good precipitation, we may be able to stop it.”
Allen said strike teams and fire engines have been requested to respond to the area.
The first calls for reinforcements came Aug. 20.
“If they have a community that is in danger, they will order a type 1, structure protection engine,” Allen said. “The first order that came in was for a wildland or type-3 engine. We were able to draw resources without depleting our own resources, and we can still fight fires here.”
Seven firefighters who are graduates from the Lake Tahoe Basin Fire Academy are helping with multiple infernos, Allen said.
“We’ve got a lot of local resources down there,” Allen said.
Fire protection agencies are monetarily reimbursed for their cooperation and resource allocation based on the number of personnel and equipment they send and how much time they spend in the area.
Of the 29 full-time firefighters and 20 seasonal firefighters, five are working the Rim Fire, a two-man chip team is working the American Fire, which is almost 25,000 acres but was 88 percent contained as of Tuesday, and a 20-person hand crew team is working on a fire in Modoc County, Allen said.
CALSTAR helicopters grounded by smoke
CALSTAR operations director Jim Arthur said that, since the smoke intensified, pilots have been unable to respond to 12 flight requests due to lack of visibility at both the South Lake Tahoe and Auburn bases.
Aircrafts, including helicopters, operate in the area under visual flight rules governed by the Federal Aviation Administration. Visibility can be measured, but it is ultimately at the pilot’s discretion whether to accept a call, Arthur said.
“They have to be able to see a certain distance in front of them, and they have to have certain distance between them and the ground,” Arthur said. “(The smoke) starts to represent a thick layer and limits visibility within regulatory requirements.”
According to FAA flight regulations, that threshold can be between one and five miles, depending on the surrounding terrain below the aircraft.
Smoke is most difficult to navigate through when it is stationary, Arthur said. When winds pick up, it can give the pilots time to fly.
There are policies to make responders aware of the no-fly situation.
“The process is the first responder makes the request for (CALSTAR), and when the flight is declined it goes back to the first responder as far as transportation for the patient,” Arthur said. “We’re disappointed that we can’t always provide the service, but we’re not doing so because of safety concerns.”
TRPA spokesman Jeff Cowen said there has been a spike in levels of nitrogen in Lake Tahoe, as 55 percent of it is vehicle emissions, wood-burning stoves, fireplaces, prescribed burns and wildfires.
The particulates are carried through the air, in this case smoke, and fall down to the lake.
The UC Davis annual “State of the Lake” report, the annual monitoring of nitrogen and other particulates will show what, if any, effect the smoke had on the lake. The report will come out next year.
“It’s a big concern, but we’re going to hold our breath and see what comes in the annual monitoring, but right now we’re not looking at the spike,” Cowen said.
Additionally, ash falling into the lake can increase turbidity levels, Cowen said.
“It does reduce clarity,” Cowen said. “We’ll see if the spike continues from nitrogen and particulates, but monitoring will show that.”
Malcom North, research scientist with the U.S. Forest Service and professor at the UC Davis Department of Plant Science, said the Rim Fire could alter the face of the forest areas it scorches.
“One of the concerns with a fire like the Rim Fire is that the forests in the Sierra Nevadas are adapted to fire, but not fire that is being produced at a high intensity,” North said.
Most of where the area of the fire is mixed conifer and brush, which still needs to burn, just not at rapidly or as hot, North said.
“A healthy forest needs a low-intensity fire,” North said. “The fire no longer burns along the surface. It gets in the crowns of the trees and moves from tree crown to crown. So the large trees are often dying in fires like this.”
As the fire takes out everything in its path, the forest cannot regenerate because there is not enough vegetation, especially trees, to repopulate the area, North said.
“You end up with areas that burn at high severity, and they often come back as brush fields because you don’t have enough trees to reseed the forest,” he said.
Some animals, too, are affected by the incendiary disaster.
“The animals that can move will get out of there, and some of them will hide underground and survive as well, but the long-term effect is where you now converted to something else. It’s fine for some animals, but it threatens other species.”
The effects on humans from smoke can have comparable effects to animals, but North said it isn’t completely known.
“The assumption is that animals would respond similarly to humans,” he said.
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