(CNN)The deadly wildfires are not only destroying homes and burning everything in their path -- but they're also causing poor air quality.
On Tuesday, a thick haze blanketed parts of the Northwest, including Seattle, as fires across the border in Canada burned. Things were looking a little better Wednesday, as cleaner air began pushing onshore, according to the National Weather Service in Seattle, which said the state had the worst air quality in the country.
Smoky haze obscures the Space Needle and downtown Seattle on August 14.
The smoke that is blanketing Washington, Oregon and California is smoke coming from the wildfires burning in British Columbia, according to the National Weather Service Seattle.
Air quality advisories were in effect for portions of Washington and Oregon, according to the weather service.
The air quality was considered unhealthy in western parts of Washington.
The unhealthy level on the Air Quality Index means that everyone could experience health effects, with possibly more serious health issues for children, seniors and people with medical conditions. Wildfire smoke can include particles from burning vegetation and building materials mixed with gases.
This was the air quality index on Tuesday, August 14, at 7 p.m. PT, according to AirNow.gov.
The Washington State Department of Natural Resources said Wednesday things had improved at bit.
"Most monitors in Western Washington are still in the unhealthy range due to lingering smoke, but more clearing is expected through tonight and tomorrow. It may be short-lived, but we expect at least a couple days of cleaner air coming up," a multiagency update said.
Wildfire smoke was visible from space as it covered parts of Washington on Tuesday.
Glacier National Park affected by fire
Also out West, firefighters are battling a lightning-caused fire at Glacier National Park that prompted evacuations and destroyed several structures.
The Howe Ridge Fire is seen on the night of August 12.
The Howe Ridge Fire ignited Saturday at the national park in Montana, spreading rapidly over the weekend. It has also sent a widespread haze of smoke in the area.
California has 11 large fires, BC has nearly 600 wildfires
As 11 large fires raged in California, there were hotspots of unhealthy air quality in certain parts of the state -- especially near the wildfires. On Tuesday, most parts of the state were considered moderate in terms of air quality, according to the EPA's AirNow site.
Also on Tuesday, Yosemite Valley, which had been closed for nearly three weeks due to a fire, reopened to visitors.
Visitors try to see through the smoke at the famous Tunnel View vista in Yosemite National Park during its reopening day.
But Yosemite National Park's website warned of poor air quality and visibility at times due to the Ferguson Fire.
Photos: Massive wildfires scorching California
A man cleans up red fire retardant dropped by a firefighting jet in Lake Elsinore, California on Sunday, August 12.
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Photos: Massive wildfires scorching California
A flag flies at half-staff amid the rubble of homes burned in the Carr Fire, on Sunday, August 12.
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Homes destroyed by a wildfire in Redding, California are seen from an aerial view on Friday, August 10
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A helicopter drops water on flames in Lake Elsinore, California, on Friday, August 10.
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Rose Wyckoff holds up three kittens August 10 in a Redding neighborhood that has been destroyed by the Carr Fire.
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King Bass, 6, and his 5-year-old sister, Princess, watch the Holy Fire burn from the top of their parents' car in Lake Elsinore on Thursday, August 9.
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Photos: Massive wildfires scorching California
Firefighters monitor a backfire while battling part of the Mendocino Complex Fire near Ladoga on Tuesday, August 7.
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Photos: Massive wildfires scorching California
A plane drops fire retardant behind homes as the Holy Fire burns in Lake Elsinore on Wednesday, August 8.
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Photos: Massive wildfires scorching California
Firefighters work on stopping the Mendocino Complex Fire, which is made up of the River and Ranch fires.
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A firefighter makes his way down a hillside while battling the Mendocino Complex Fire on August 7.
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A supertanker jet flies above the Holy Fire near Lake Elsinore on August 7.
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Crystal Easter comforts her dogs as they flee a wildfire in Spring Valley on Monday, August 6.
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The Carr and Ferguson fires are visible from space in an image taken by European Space Agency astronaut Alexander Gerst on Friday, August 3.
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Ventura County firefighters watch as a helicopter makes a drop on a hot spot in Scotts Valley on August 3.
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An airplane drops fire retardant in Lakeport on Thursday, August 2.
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Flames from a wildfire move up a ridge near Lakeport on August 2.
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Flames from a wildfire advance down a hillside near Lakeport on August 2.
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A firefighter walks around a swimming pool that had been sprayed by fire retardant near Lakeport.
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An air tanker drops fire retardant near Redding on August 2.
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A tower of smoke pours from Cow Mountain as a firefighter keeps a watch on surrounding vegetation.
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The Carr Fire can be seen from a commercial flight flying over Redding on Wednesday, August 1.
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Photos: Massive wildfires scorching California
Firefighters conduct a controlled burn to defend houses from the Ranch Fire as it moves toward Upper Lake.
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Photos: Massive wildfires scorching California
The Ranch and River fires make up the Mendocino Complex Fire, which has been raging in and near the southeast corner of the Mendocino National Forest, northwest of Sacramento.
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A barn burns on Tuesday, July 31, as the River Fire moves through Lakeport.
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A firefighter runs while trying to save a house in Lakeport.
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Firefighters try to control a back burn as the Carr Fire spreads toward the towns of Douglas City and Lewiston on July 31.
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Photos: Massive wildfires scorching California
A woman leaves Lakeport as the River Fire approaches on July 31.
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A house burns as the River Fire moves through the Lakeport area on July 31.
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Firefighters in Upper Lake watch a back burn on July 31.
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The Carr Fire leaves cars destroyed near Redding on July 31.
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Fire retardant is dropped near a home as the Mendocino Complex Fire burns near Lakeport on Monday, July 30.
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A firefighter walks through smoke while fighting to save a winery in Lakeport on July 30.
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A house near Finley burns from the Mendocino Complex Fire on July 30.
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Boats sit at Whiskeytown Lake, near where the Carr Fire originated, on Sunday, July 29.
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Deer graze along a road covered in fire retardant as the Carr Fire burns near Redding on Saturday, July 28.
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A fire truck drives along Highway 299 as the Carr fire continues to burn near Whiskeytown on July 28.
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The setting sun is turned red by smoke from the Carr Fire on Friday, July 27.
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Burned-out properties are seen in Redding on July 27.
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A firefighting helicopter makes a water drop as the sun sets over a ridge burning near Redding on July 27.
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A large pyrocumulus cloud explodes near Redding on July 27.
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Flames from the Carr Fire burn through trees near Whiskeytown on July 27.
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A burning home is reflected in a pool in Redding on July 27.
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A firefighter monitors a backfire while battling the Carr Fire on July 27. The fire grew rapidly, ravaging several small communities and jumping the Sacramento River before threatening the outskirts of Redding.
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A firefighter lights backfires in Redding on July 27.
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The Cranston Fire burns in San Bernardino National Forest, near Idyllwild, on Thursday, July 26. The Cranston Fire has prompted thousands to flee their homes.
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The Carr Fire burns along Highway 299 on July 26.
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The Carr Fire tears through Shasta on July 26.
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A historic schoolhouse burns in Shasta on July 26.
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A firefighter walks along Highway 299 as the Carr Fire tears through Shasta on July 26.
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Smoke from the Ferguson Fire fills California's Yosemite Valley on Wednesday, July 25. Some of the most iconic areas of Yosemite National Park were forced to close because of the wildfire.
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In British Columbia, more than 10,000 homes across the province are on alert to evacuate due to the nearly 600 wildfires burning, BC Wildfire Service spokesman Kevin Skrepnek said.
