A fire truck drives past burning trees as firefighters continue to battle the Rim Fire near Yosemite National Park, Aug. 26, 2013. CREDIT: Jae C. Hong/AP
(USATODAY.com) - Higher humidity helped crews battling the giant wildfire at the edge of Yosemite National Park in California on Wednesday, but the smoky haze it has produced triggered emergency air quality warnings more than 100 miles away in Nevada.
The U.S. Forest Service said the fire grew to just over 300 square miles by Wednesday night and was 30% contained. The Forest Service estimates it will not be fully contained until at least Sept. 10.
"Our crews are getting the upper hand on this fire," said Daniel Berlant of the California Department of Forestry and Fire Protection, or Cal Fire.
Officials were shutting down the second of the four access routes into the park, with the closure of Tioga Road on the west side. The route was being closed to allow fire crews to build containment lines along the road before the approach of the fire.
While the fire has burned into the park, most of the burned area is in the Stanislaus National Forest just west and north of the park in the Sierra Nevada mountains.
Last week, a stretch of Highway 120 that serves as the main entrance from the San Francisco Bay area was closed.
The Forest Service said crews used backfires to try to stop the advance of the fire further into the park and around the Hetch Hetchy reservoir that sends water to the San Francisco area.
Yosemite officials say the most visited areas of the park, including Yosemite Valley, remain open and largely unaffected by the fire in advance of the Labor Day weekend, when the park normally swells with holiday visitors.
The Rim Fire has burned 192,466 acres, destroyed 111 structures and threatened water supplies, hydroelectric power and giant sequoias. The cause of the fire remains under investigation, according to Cal Fire.
More than 4,500 firefighters were battling the blaze. Forest Service officials said in their latest report that crews were heavily dependent on air tankers, including modified C-130 and DC-10 planes, because of difficult, inaccessible terrain where the fire is moving.
The fire was already the seventh largest ever in California.
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The effects of the stubborn fire could be felt far and wide. For the second time in a week, schoolchildren were kept indoors in Reno and Carson City, and officials urged people to avoid all physical activity outdoors.
Air quality officials from the Washoe County health district declared unhealthy conditions in the Reno/Sparks area for the general population, not just those people in sensitive groups. Officials warned that conditions could deteriorate to "very unhealthy" conditions depending on wind direction, the Reno Gazette-Journalreports.
"People with respiratory or heart disease, the elderly and children should avoid prolonged or heavy exertion; everyone else should limit or avoid prolonged or heavy exertion," the statement said. "In general, if you smell smoke and feel it's affecting you, then take precautions such as: staying indoors with the windows and doors closed and the air conditioner on; limiting outdoor exertion and physical activity; and, drinking plenty of fluids."