Here’s what to know as a summer of wildfires prompts air-quality alerts across the West

correction

A previous version of this article said the air quality index in Washoe County, Nev., reached 291 on Sunday. It reached that level Monday. It also said air-conditioning units pull in outside air. Some do that; others recirculate indoor air or have vents that can be closed. The article has been corrected.

Thick smoke blanketed the area around Reno, Nev., in recent days, plumes wafting over the mountains from wildfires burning in Northern California and settling in the valley, fueling record bad air quality.

This week, the area experienced its top three worst air pollution days on record, according to Washoe County officials.

“Visibility can be less than a mile at times, so these beautiful tree-covered and a lot of times snow-covered mountains we’re used to seeing are gone right now,” said Craig Petersen, a senior air quality specialist for Washoe County, describing the scene when smoke levels were high.

In several states across the West, smoke from the largest of numerous active blazes is prompting warnings about the air quality. Alerts warning the public about pollution levels remained in effect Thursday in parts of Nevada, Oregon, Washington, Idaho and Wyoming, according to a map on the National Weather Service website, largely because of wildfire smoke. Such alerts were also issued in parts of Minnesota and Wisconsin because of smoke drifting from the Greenwood Fire burning in northeast Minnesota.

Forecasters and experts say there will probably be varying levels of air quality issues because of fires for some time, so residents should take precautions.

Jennifer Richmond-Bryant, an associate professor at North Carolina State University’s department of forestry and environmental resources, said it “seems like it’s becoming more common” to see widespread air quality issues.

“Right now you have several large fires in the West so it would make sense that you would have air quality alerts in so many places,” she said.

In addition to the Weather Service map that relays areas with current air quality alerts and advisories, the Environmental Protection Agency and U.S. Forest Service launched the AirNow Fire and Smoke Map to keep track of air quality and provide information about conditions by location. The EPA said the map pulls information from monitors such as those stationed near fires and other sensors that measure fine particle pollution, since particles are the major harmful pollutant in smoke.

The EPA’s AirNow site explains how to interpret the color-coded air quality index, or AQI. The green level, with the lowest AQI of 50 and under, means the air pollution “poses little or no risk,” while the maroon level with an AQI of 301 or higher denotes a “health warning of emergency conditions: Everyone is more likely to be affected.” Local agency websites also provide resources for tracking air quality. In Oregon, for example, a smoke information blog shows active fires and the state’s current air quality.

This week, the Washoe County air quality management division tweeted updates about the troubling trends as plumes from the Dixie Fire, the second-largest wildfire in California history, and the massive Caldor Fire, the fast-growing blaze creeping toward Lake Tahoe, drifted into the area.

On Monday, the AQI in Washoe County reached 291, the worst since the county began monitoring PM 2.5, harmful fine particulates small enough to penetrate deep into the lungs, Petersen said. That’s a level considered “very unhealthy,” with the risk of health effects elevated for all populations.

A photo the county shared Tuesday put the troubling conditions in stark relief: A dense haze covered the view of the town and far-off mountains that are usually visible.

Raging wildfires in Northern California have affected air quality across the United States. (Video: Julie Yoon/The Washington Post)

In addition to warnings from national and local resources and officials, Richmond-Bryant said air quality information is also readily available on weather apps. She described pulling up the weather app on her phone to see the air quality level right below the temperature forecast and an indicator explaining the current AQI level.

There’s also another way to tell whether the air quality spells trouble: “If it smells smoky, that’s bad news,” said Anthony Wexler, director of the Air Quality Research Center at the University of California at Davis. “If you can look at the sun and it doesn’t hurt your eyes, that’s also a really bad sign, because that smoke is blocking the sun.”

While experts say anyone can be negatively affected by wildfire smoke, Wexler said for people of normal health, “you don’t want to be going out of your way to breathe this stuff, but you don’t need to go out of your way to avoid it either.”

“People shouldn’t panic about this and run for cover, but you should try to minimize your exposure because we know it’s not good for you,” he said.

Smoke is primarily composed of particulate matter, and Richmond-Bryant said there’s evidence that short-term exposure to particulate matter can lead to increased cardiovascular events. Exposure can also cause respiratory illnesses such as asthma, she said.

People with asthma or other preexisting diseases, as well as young children and the elderly, are especially vulnerable to the hazards of wildfire smoke, experts said. Wexler said people who do manual labor outdoors can also be vulnerable, because they’re breathing more of and are exposed to a higher level of air pollution while outside.

Petersen said when air quality is at particularly troubling levels, the best thing is to avoid the smoke and stay indoors.

If people have whole-home air conditioning, installing high-efficiency filters and running the system can filter smoke that’s gotten inside. Some window air-conditioning units pull in outside air, Petersen said, while others pull in indoor air. He said some window units have vents that can be closed, with a lever that can be pulled to keep outside air out.

“If you don’t have an air conditioner, create a clean room: Hunker in a room that doesn’t have any doors leading to the outside or windows leading to the outside,” he said. The EPA has a website explaining how to create a clean room to “help reduce your exposure to smoke while staying indoors.”

For those going outside, properly used masks can help.

Richmond-Bryant said while people are now used to using masks to protect against the coronavirus, normal cloth masks may not have enough protection against wildfire smoke. Instead, people should opt for N95-type masks that form a tight seal around the nose and mouth.

As long as fires continue to burn, smoke will continue drifting into surrounding areas. Across the country, 88 large fires are actively burning, according to the National Interagency Fire Center.

Bob Oravec, a lead forecaster with the National Weather Service, warned that unless there is marked progress in fire containment, weather conditions may not help to alleviate the fires until the fall.

“It doesn’t appear there will be any pattern change in the weather that’s going to bring any significant improvement with respect to precipitation,” Oravec said. “With respect to weather conditions, it doesn’t look very favorable going forward.”

That could mean that parts of the country could see air quality alerts at various times for the remainder of the summer.

“Different communities are going to get hit by this stuff depending on if they’re downwind of the fires or not,” Wexler said.

Map data from NOAA Global Systems Laboratory.

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