Wildfires in the Western U.S. continue to blaze, with much of the activity centered in California, Idaho, Oregon and Washington.

In Oregon and Washington, 28 large fires are burning across 1.5 million acres. But the Bureau of Land Management notedthat for a number of the major fires, their growth has slowed. The large Beachie Creek Fire east of Salem, Ore., had recorded no new growth in the previous day.

About 8,500 firefighters have been deployed in the two states, but smoky conditions have hindered the use of aircraft or helicopters to fight the blazes.

Rain should help the effort to contain the fires, though major precipitation isn't expected. Showers are forecast in northwest Oregon and along the Cascades, and the increase in relative humidity should improve conditions, according to the National Interagency Fire Center.

But critically dry conditions are expected to continue across eastern Oregon, California, Nevada and western Montana, joined by gusty winds.

Alaska Airlines temporarily suspended its flights in Portland, Ore., and Spokane, Wash., due to wildfire smoke.

A haze from the fires drifted across much of the U.S., and was noticeable in New York City and Washington, D.C.

In California, over 16,600 firefighters are battling 25 major wildfires. Wildfires have burned over 3.2 million acres in the state since the beginning of the year. Fire activity in the state increased in mid-August, and have caused 25 deaths and destroyed more than 4,200 structures, according to CalFire.

The August Complex fire, which started nearly a month ago, has burned through more than 755,000 acres in Mendocino and Humboldt County. It's now 30% contained.

The North Complex Fire, near Chico, has destroyed at least 723 structures and killed 15 people. Now burning for 27 days, it's just 39% contained.

The Creek Fire, in Fresno County, has burned more than 220,000 acres and is only 16% contained. The Dolan Fire, about 10 miles south of Big Sur, is just 40% contained and has burned nearly 120,000 acres.

Scientists have linked an increasing prevalence and intensity of wildfires to climate change, and residents of Western states are grappling with the dread that severe fire seasons are the new normal.

Five of the largest wildfires in California history have occurred this year.

Wildfire smoke can irritate lungs, cause inflammation, affect the immune system, and increase the possibility of lung infections including the virus that causes COVID-19, the Centers for Disease Control cautions.

The National Weather Service warns that cloth face coverings to protect against COVID-19 do not protect against wildfire smoke.

Instead, it suggested: "Stay inside and close windows and doors. If you're running an air conditioner, keep the fresh-air intake closed and clean the filter to prevent outdoor smoke from getting inside."

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