A thin cloud of smoke hung over the Western United States, the upper Midwest and into Canada this week fueled by forest fires in California, Oregon, Washington, Idaho and the greater Yellowstone area.
The red skies of sundown have become a familiar sight over the past decade, with a steady increase in large fires, especially in Idaho. That has created a new phenomenon called the “smoke wave,” coined by a team of Harvard researchers. Smoke waves are two or more consecutive days of unhealthy levels of particulate pollution from fires. Think heat wave, measured by hazy skies instead of rising mercury.
For the Treasure Valley, smoke waves have become almost an annual event, as they have for mountain towns like McCall and Stanley.
Julia Mickley was working on a fire-management team in McCall in 2015 when she described to her aunt the smoky conditions she often faced that summer: Light gray smog in the valley, making visibility poor.
“She had trouble running,” said her aunt, Loretta Mickley, one of the researchers from Harvard’s School of Engineering and Applied Sciences. “That’s something, since she runs in marathons.”
TINY PARTICLES IN SMOKE
Mickley and the team published a paper in July that showed that longer, drier and hotter fire seasons caused by the changing climate already are a public health problem, increasing the number of days when wildfire smoke containing PM 2.5 — the tiniest particulate matter, 2.5 microns or smaller — pollutes the air at unhealthy levels.
Those small particulates from smoke get breathed into our lungs and directly into the bloodstream, worsening chronic heart and lung disease and, when thick enough, irritating the respiratory systems of even healthy people.
The Harvard scientists used fire and atmospheric modeling to focus on pollution caused by wildfires and the way that pollution moves. What the Harvard scientists found was that, when the air was unhealthy, 71 percent of the pollution across the West between 2004 and 2009 came from wildfire smoke. By 2051, the study predicts, the growing number and severity of fires in Idaho will mean a doubling of smoke waves.
“All of the predictions showed rising temperatures will increase the number of smoke waves people will experience in the future,” Mickley said. “Idaho will be particularly hard hit.”
Large fires in Idaho, like the Pioneer Fire near Lowman that now exceeds 100,000 acres, have become routine over the past 25 years. Idaho Department of Environmental Quality air monitoring data show that smoke waves in the Treasure Valley line up with big fire years.
In 2007, large fires burned all around the Valley beginning in July and running through September. In 2012, the Trinity Ridge Fire in the Boise National Forest sent smoke down the Middle Fork of the Boise River repeatedly in August and September, filling the Valley with smoke. The Pony and Elk Creek fires south of Boise caused several smoke waves in 2013.
In 2015 it was the Soda Fire in Owyhee County that smoked up the region, and in October, long past when fire season is historically over, the Walker Fire between Boise and Idaho City spilled unhealthy levels of smoke into the Treasure Valley.
Despite the health impacts, the U.S. Environmental Protection Agency and the Idaho DEQ don’t count these smoke-related events as violations of air health standards. Smoke is considered uncontrollable and labeled an extraordinary event.
“There’s nothing we can do,” said Bruce Louks, manager for Idaho DEQ’s air modeling and emissions group. “If it doesn’t affect regulatory outcomes, EPA may not review it.”
That doesn’t mean officials do nothing. For years, EPA and DEQ have worked with counties, other state agencies, tribes and federal agencies to coordinate burning and to inform the public when smoke levels are high. A statewide blog gives local communities a guide to smoke levels and weather conditions that carry the smoke to them. Bad air can prompt advice to reduce strenuous activity and stay indoors.
Smoke levels are regular parts of Idaho weather reports.
WHAT WE CAN DO
For residents with asthma, chronic obstructive pulmonary disease and heart disease, it doesn’t take a high level of smoke to cause problems breathing and limitations on activity. And residents don’t have to be able to see the smoke to have it affect them.
“We see an exacerbation of symptoms in people with chronic respiratory ailments this time of year,” said Don Beasley, an ear, nose and throat doctor at St. Alphonsus Regional Medical Center.
When those patients have to go outside in smoky conditions, Beasley recommends they wear a mask.
“The best measure is just avoid it and stay indoors, avoiding strenuous activities,” Beasley said.
Harvard’s Mickley said forest thinning and other fuel-reducing actions, including intentional burns in spring and fall, may help able to reduce summer fire smoke in some areas. The fact that most of the Boise and Payette national forests in Southwest Idaho already have burned over the past 30 years may reduce local wildfire smoke in the near future.
“With careful fire-management strategies,” said Mickley, “some of this could be avoided.”
The Forest Service has had a program for five years to address smoke and air quality concerns in firefighting management. In 2015, the EPA had one of its smoke-management leaders, Mike McGown of Boise, working with fire-incident command teams to help reduce smoke when possible.
“We want to have people with meteorology and air quality-modeling expertise out on the fire tied in with the incident command,” McGown said.
Health effects from smoke
Smoke from wildfires is a mixture of gases and fine particles from burning trees and other plant materials, according to Heather Kimmel, executive director of the American Lung Association in Idaho.
Smoke can irritate respiratory systems and worsen chronic heart and lung diseases. Smoke is the smallest particle pollutant; known as PM 2.5, these 2.5-micron particles are about 1/30th the diameter of a human hair and smaller.
Our natural defenses help us cough or sneeze out the larger particles, but smaller PM 2.5 particles can get trapped in the lungs and are too small to be coughed out. The smallest are so small they can pass through the lungs into the bloodstream.
The effects are not cumulative, said Don Beasley, a St. Alphonsus Regional Medical Center doctor.