GROVELAND, Calif. -- The giant wildfire burning at the edge of Yosemite National Park has not only destroyed buildings and threatened water supplies, electricity and sequoias, it has also unleashed a smoky haze that has worsened air quality more than 100 miles away in Nevada.


The plume from the Rim Fire in California triggered emergency warnings in the Reno and Carson City area. Schoolchildren were kept inside for the second time in a week, people went to hospitals complaining of eye and throat irritation and officials urged people to avoid all physical activity outdoors.


"It's five hours away," said 22-year-old bartender Renee Dishman in disbelief after learning that the source of the haze was more than 150 miles away. "I can't run. I can't breathe. It makes me sneeze."


The Rim Fire, so far, has burned through 280 square miles, destroyed 23 structures and threatened water supplies, hydroelectric power and giant sequoias. On Tuesday night, authorities said the blaze was 20 percent contained.


In Nevada, the biggest impact of the Rim Fire was on the air. The air quality index briefly surpassed the rare "hazardous" level east of Lake Tahoe before improving slightly. It hovered around the next-most serious stage of "very unhealthy" for all populations in the Reno-Sparks area 30 miles north.


Dennis Fry, a Reno auto body specialist for nearly 30 years, remembered smoke this thick when he worked on a logging crew and helped fight fires in Oregon during the 1970s.


"But never in Reno, not this bad," he said. "You could actually see the smoke inside my body shop."


Everyone should avoid all physical activity outdoors when the air quality index reaches "hazardous," considered "emergency conditions," the Nevada Division of Environmental Protection said on its website. "People with heart or lung disease, older adults and children should remain indoors and keep activity levels low."


Renown Regional Medical Center in Reno has experienced a "slight increase" in emergency room visits as a result of the smoke, said Jennifer Allen, the hospital's clinical nursing supervisor.



"Patients are experiencing shortness of breath, eye and throat irritation, cough and headache due to the heavy smoke and poor air quality," she said, adding that people with asthma and other respiratory ailments were most affected.


The pollution levels are among the worst ever recorded for small particulates around Carson City in the state's air monitoring records dating to 2000, according to JoAnn Kittrell, public information manager for Nevada Division of Environmental Protection. The air quality briefly moved into the "hazardous" level in some areas on Friday as well, she said.


"It's very unusual," she said. "We just happen to be in the direct path of the plume from Yosemite."


The previous peak reading in Reno came on Friday when the air quality index closed in on the "very unhealthy" stage. Schoolchildren were kept indoors during recess, high school football practices and scrimmages were canceled through the weekend and an annual air show at Lake Tahoe was canceled due to low visibility.


Carol Chaplin, executive director Lake Tahoe Visitors Authority, said some hotels and motels reported cancellations earlier in the week, but so far there hasn't been any major impact for the upcoming Labor Day weekend. "I could lie and say it's not affecting anything, but it is," she said. She said visibility in the scenic Tahoe Basin ebbs and flows with the shifting winds.


"I still see people out on the lake," she said. "At least we're not on fire."


The fire caused air pollution problems in California cities far away from the fire, including those in the Sacramento region.


Two dozen competitors in the 25th annual Best in the West Nugget Rib Cook-Off were taking it in stride as they prepped their grills for the barbeque festival running Wednesday through Labor Day in Sparks. The air around the event is usually filled with smoke, albeit a different kind when the barbeque festival's in town.


"You can't have too much smoke at a barbeque," said Mike Peters of Springfield, Mo., a member of the Kansas City Barbeque Society's Great American Barbeque Tour Team. "We're just going to add a little hickory smell to it."


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Associated Press Carson City correspondent Sandra Chereb contributed to this report.



Earlier on HuffPost:




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  • In this undated photo provided by the U.S. Forest Service, the Rim Fire burns near Yosemite National Park, Calif. The wildfire outside Yosemite National Park — one of more than 50 major brush blazes burning across the western U.S. — more than tripled in size overnight and still threatens about 2,500 homes, hotels and camp buildings. Fire officials said the blaze burning in remote, steep terrain had grown to more than 84 square miles and was only 2 percent contained on Thursday, down from 5 percent a day earlier. (AP Photo/U.S. Forest Service)




  • Rim Fire Burns Near Yosemite National Park


    GROVELAND, CA - AUGUST 22: A firefighter from Central Calaveras Fire monitors the Rim Fire on August 22, 2013 in Groveland, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 1,000 firefighters are battling the blaze that was reduced to only 2 percent containment after it nearly tripled in size overnight. (Photo by Justin Sullivan/Getty Images)




  • Rim Fire Burns Near Yosemite National Park


    YOSEMITE NATIONAL PARK, CA - AUGUST 22: Smoke from the Rim Fire is visible near the Hetch Hetchy reservoir on August 22, 2013 in Yosemite National Park, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 1,000 firefighters are battling the blaze that was reduced to only 2 percent containment after it nearly tripled in size overnight. (Photo by Justin Sullivan/Getty Images)




  • Rim Fire Burns Near Yosemite National Park


    GROVELAND, CA - AUGUST 22: A firefighting helicopter flies in front of a plume of smoke from the Rim Fire on August 22, 2013 in Groveland, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 1,000 firefighters are battling the blaze that was reduced to only 2 percent containment after it nearly tripled in size overnight. (Photo by Justin Sullivan/Getty Images)




  • In this undated photo provided by the U.S. Forest Service, the Rim Fire burns near Groveland Ranger Station in Groveland, Calif. The wildfire outside Yosemite National Park — one of more than 50 major brush blazes burning across the western U.S. — more than tripled in size overnight and still threatens about 2,500 homes, hotels and camp buildings. Fire officials said the blaze burning in remote, steep terrain had grown to more than 84 square miles and was only 2 percent contained on Thursday, down from 5 percent a day earlier. (AP Photo/U.S. Forest Service)




  • Rim Fire Burns Near Yosemite National Park


    GROVELAND, CA - AUGUST 22: Firefighters from the Colorado based South Arkansas Fire District monitor the Rim Fire on August 22, 2013 in Groveland, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 1,000 firefighters are battling the blaze that was reduced to only 2 percent containment after it nearly tripled in size overnight. (Photo by Justin Sullivan/Getty Images)




  • Rim Fire Burns Near Yosemite National Park


    GROVELAND, CA - AUGUST 22: Firefighters monitor a plume of smoke from the Rim Fire on August 22, 2013 in Groveland, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 1,000 firefighters are battling the blaze that was reduced to only 2 percent containment after it nearly tripled in size overnight. (Photo by Justin Sullivan/Getty Images)




  • Rim Fire Burns Near Yosemite National Park


    GROVELAND, CA - AUGUST 22: A U.S. Forest Service firefighter monitors a radio while battling the Rim Fire on August 22, 2013 in Groveland, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 1,000 firefighters are battling the blaze that was reduced to only 2 percent containment after it nearly tripled in size overnight. (Photo by Justin Sullivan/Getty Images)




  • Rim Fire Burns Near Yosemite National Park


    GROVELAND, CA - AUGUST 22: A firefighter from the Kern County Rio Bravo Hotshots looks for flying embers while battling the Rim Fire on August 22, 2013 in Groveland, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 1,000 firefighters are battling the blaze that was reduced to only 2 percent containment after it nearly tripled in size overnight. (Photo by Justin Sullivan/Getty Images)




  • Rim Fire Burns Near Yosemite National Park


    GROVELAND, CA - AUGUST 22: Firefighters douse hot spots while battling the Rim Fire on August 22, 2013 in Groveland, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 1,000 firefighters are battling the blaze that was reduced to only 2 percent containment after it nearly tripled in size overnight. (Photo by Justin Sullivan/Getty Images)




  • Rim Fire Burns Near Yosemite National Park


    GROVELAND, CA - AUGUST 21: Firefighters from Ebbetts Pass Fire District monitor a back fire as they battle the Rim Fire on August 21, 2013 in Groveland, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 400 firefighters are battling the blaze that is only 5 percent contained. (Photo by Justin Sullivan/Getty Images)




  • Rim Fire Burns Near Yosemite National Park


    GROVELAND, CA - AUGUST 21: A firefighter from Ebbetts Pass Fire District uses a drip torch to light a back fire as they battle the Rim Fire on August 21, 2013 in Groveland, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 400 firefighters are battling the blaze that is only 5 percent contained. (Photo by Justin Sullivan/Getty Images)




  • Rim Fire Burns Near Yosemite National Park


    GROVELAND, CA - AUGUST 21: Firefighters from Ebbetts Pass Fire District monitor a back fire as they battle the Rim Fire on August 21, 2013 in Groveland, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 400 firefighters are battling the blaze that is only 5 percent contained. (Photo by Justin Sullivan/Getty Images)




  • Rim Fire Burns Near Yosemite National Park


    GROVELAND, CA - AUGUST 21: A firefighter from Ebbetts Pass Fire District monitors a back fire as he battles the Rim Fire on August 21, 2013 in Groveland, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 400 firefighters are battling the blaze that is only 5 percent contained. (Photo by Justin Sullivan/Getty Images)




  • Rim Fire Burns Near Yosemite National Park


    GROVELAND, CA - AUGUST 21: Firefighters from Ebbetts Pass Fire District monitor a back fire as they battle the Rim Fire on August 21, 2013 in Groveland, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 400 firefighters are battling the blaze that is only 5 percent contained. (Photo by Justin Sullivan/Getty Images)




  • Rim Fire Burns Near Yosemite National Park


    GROVELAND, CA - AUGUST 21: A firefighter from Ebbetts Pass Fire District uses a drip torch to light a back fire while battling the Rim Fire on August 21, 2013 in Groveland, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 400 firefighters are battling the blaze that is only 5 percent contained. (Photo by Justin Sullivan/Getty Images)




  • Rim Fire Burns Near Yosemite National Park


    BUCK MEADOWS, CA - AUGUST 21: Fire consumes trees along US highway 120 as the Rim Fire burns out of control on August 21, 2013 in Buck Meadows, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 400 firefighters are battling the blaze that is only 5 percent contained. (Photo by Justin Sullivan/Getty Images)




  • Rim Fire Burns Near Yosemite National Park


    GROVELAND, CA - AUGUST 21: Fire consumes trees along US highway 120 as the Rim Fire burns out of control on August 21, 2013 in Groveland, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 400 firefighters are battling the blaze that is only 5 percent contained. (Photo by Justin Sullivan/Getty Images)




  • Rim Fire Burns Near Yosemite National Park


    GROVELAND, CA - AUGUST 22: A DC-10 air tanker drops fire retardant on a ridge ahead of the advancing Rim Fire on August 22, 2013 in Groveland, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 1,000 firefighters are battling the blaze that was reduced to only 2 percent containment after it nearly tripled in size overnight. (Photo by Justin Sullivan/Getty Images)




  • Rim Fire Burns Near Yosemite National Park


    GROVELAND, CA - AUGUST 22: Charred manzanita bushes are seen as the sun rises through thick smoke during the Rim Fire on August 22, 2013 in Groveland, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 1,000 firefighters are battling the blaze that was reduced to only 2 percent containment after it nearly tripled in size overnight. (Photo by Justin Sullivan/Getty Images)




  • Rim Fire Burns Near Yosemite National Park


    GROVELAND, CA - AUGUST 21: The sun sets through heavy smoke from the Rim Fire on August 21, 2013 in Groveland, California. The Rim Fire continues to burn out of control and threatens 2,500 homes outside of Yosemite National Park. Over 400 firefighters are battling the blaze that is only 5 percent contained. (Photo by Justin Sullivan/Getty Images)